Friday, February 1, 2013

Learning Natural Tangent Tables

The branch of math that deals with the relations of the sides and angles of triangles is known as trigonometry. Which the methods of reducing from a certain given parts to other required parts, and also in the general relations which exist between the trigonometrical functions of arcs or angles. The trigonometry ratio table is used to find the values of the trigonometry functions. Here we are going to see about learning of natural tangent tables:

The natural tangent of an angle is the ratio, the length of the opposite side to the length of the adjacent side. In our case

Tan A = `(opposite side) / (adjacent side)`

The natural tangent angle table will be very useful for finding the value of tangent angles. Learning of natural tangent tables will be very helpful when we are using the problems.


Learning Natural Tangent Tables:

Angle   Tangent(A) Angle    Tangent (A) 
0         0.000
1         0.017
2         0.035
3         0.052
4         0.070
5         0.087
6         0.105
7         0.123
8         0.141
9         0.158
10        0.176
11        0.194
12        0.213
13        0.231
14        0.249
15        0.268
16        0.287
17        0.306
18        0.325
19        0.344
20        0.364
21        0.384
22        0.404
23        0.424
24        0.445
25        0.466
26        0.488
27        0.510
28        0.532
29        0.554
30        0.577
31        0.601
32        0.625
33        0.649
34        0.675
35        0.700
36        0.727
37        0.754
38        0.781
39        0.810
40        0.839
41        0.869
42        0.900
43        0.933
44        0.966
45        1.000
45        1.000
46        1.036
47        1.072
48        1.111
49        1.150
50        1.192
51        1.235
52        1.280
53        1.327
54        1.376
55        1.428
56        1.483
57        1.540
58        1.600
59        1.664
60        1.732
61        1.804
62        1.881
63        1.963
64        2.050
65        2.145
66        2.246
67        2.356
68        2.475
69        2.605
70        2.747
71        2.904
72        3.078
73        3.271
74        3.487
75        3.732
76        4.011
77        4.331
78        4.705
79        5.145
80        5.671
81        6.314
82        7.115
83        8.144
84        9.514
85        11.430
86        14.301
87        19.081
88        28.636
89        


Examples for Learning Natural Tangent Tables:

Find the values of the given natural tangent angles using natural tangent table.

1) tangent 1   =      0.017

2) tangent 48   =   1.1114

3) tangent 9   =     0.158

4) tangent 56  =     1.483

5) tangent 16   =     0.287

6) tangent 64   =     2.050

7) tangent 25    =    0.466

8) tangent 78    =    4.705

9) tangent 44   =    0.966

10) tangent 88   =    28.636

Thursday, January 31, 2013

Multiplication tables

In this article we are going to see about multiplication tables.  Multiplication facts table lets you learn and practice the basic time tables using the numbers zero through twelve. Children are no longer memorizing their multiplication facts table. There are many tricks to teach children multiplication facts table in mathematics.

Simplest Method for Multiplication Facts Table

Remember, work on the 2's, 5's and 10's  first; then the doubles (6x6, 7 x7, 8x8); then move to each of the fact families: 3's, 4,s, 6's, 7's, 8's and 9's, 11's and 12's. Don’t move to a different fact family without mastering the previous one.

Simplest method for multiplication facts table:


x 0 1 2 3 4 5 6 7 8 9 10 11 12
0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 0 1 2 3 4 5 6 7 8 9 10 11 12
2 0 2 4 6 8 10 12 14 16 18 20 22 24
3 0 3 6 9 12 15 18 21 24 27 30 33 36
4 0 4 8 12 16 20 24 28 32 40 40 44 48
5 0 5 10 15 20 25 30 35 40 45 50 55 60
6 0 6 12 18 24 30 36 42 48 54 60 66 72
7 0 7 14 21 28 35 42 49 56 63 70 77 84
9 0 8 16 24 32 40 48 56 64 72 80 88 96
9 0 9 18 27 36 45 54 63 72 81 90 99 108
10 0 10 20 30 40 50 60 70 80 90 100 110 120
11 0 11 22 33 44 55 66 77 88 99 110 121 132
12 0 12 24 36 48 60 72 84 96 108 120 132 144


Your life will be lot easier when you can simply remember the multiplication facts table. Please train your memory.  First, you can use the multiplication facts table above to start putting the answers into your memory. Use it a few times per day for about 10 minutes each, and you will learn your multiplication tables.

Wednesday, January 30, 2013

Graph of Y Square Root of X

Generally a function is described in the form y = f(x), y being the value the function at any general point x in the domain of the function. The letter y is chosen because the values of the function is represented by the y-axis in a graph.

The graph of the function gives a visual presentation of the function which helps us to study the function at a glance.

The values of square root of positive real numbers is expressed as function f(x) = square root of x or simply y = square root of x. The graph of y = square root of x is an interesting study and let us take a closer look.


Concept of a Square Root Function:

Consider a simple square function y = x2. It is a special  form of a quadratic function. We know that the graph of a quadratic function is a parabola. In this case it is a vertical, concave up parabola with origin as vertex. The graph is shown below.

graph y= x^2

Let see what is the inverse of the function y = x2

y = x2, or, √y = x and by interchanging the variable we get the inverse function as,

y = √x

Thus the square root function is nothing but the inverse of the square function.

We had seen that the graph of y = = x2 is symmetrical over y –axis. Therefore, the graph of y = square root of x has to be symmetrical over x-axis. However, since negative values of root of x have no meaning, the graph exists only in the first quadrant of the Cartesian system. It is shown below.

graph of y square root of x


Example Problems on Graph of Y Square Root of X

From the graph of y square root of x, find the value of square root 3 to the nearest tenths. (Assume the sale to be 1unit on both the axes)

graph of y square root of x

Since the scale of the graph is 1 unit each small division represents 0.2 unit. It is seen from the graph, when x = 5, the value of y is 1.7. Hence, square root of 3 is 1.7, nearest to tenths.

Use the graph of y square root of x, to evaluate 2( square root 6) to the nearest tenths. (Assume the sale to be 1unit on both the axes)

graph of y square root of x

Since the scale of the graph is 1 unit each small division represents 0.2 unit. It is seen from the graph, when x = 6, the value of y is 2.5. Hence, 2(square root of 6) = 2(2.5) = 5

Monday, January 28, 2013

Solve Cumulative Probability Distribution Function

Computation of probability of events is called as probability distribution.  It can give all possible outputs in a single process.  Cumulative probability distribution function of a random variable X is defined as F(x) = P(X <= x) = sum_(x)I <= x)p(x_i): (-oo < x oo).  Let us discuss about the topic of “solve cumulative probability distribution function” in the following below with some related problems.

Example Problems – Solve Cumulative Probability Distribution Function

Example problem 1

A random variable Y has the following probability mass function.  Find the value of b and evaluate `P(Y lt= 2)` .

Y01234
P(Y = y)10b20b30b40b50b

Solution:

P(Y = y) is the probability mass function `sum_(y = 0)^4 (Y = y) = 1`

P(Y=0) + P(Y = 1) + P(Y = 2) + P(Y = 3) + P(Y = 4) = 1

10b + 20b + 30b + 40b + 50b = 1

150b = 1

b = `1/150`

`P(Y lt= 2) = P(Y = 0) + P(Y = 1)`

                = `10/150 + 20/150 + 30/150`

                = `(10 + 20 + 30)/150`

                = `60/150`

                = `2/5`

Answer:

The value of b is `1/150`
`P(Y lt= 2) = 2/5`

Example problem 2

Find out probability mass function and cumulative distribution function for getting ‘4’s when two dice are thrown.

Solution:

Let us consider Y be the random variable of getting number of ‘4’s.

First, we are going to find the probability mass function

Therefore, Y can take the values 0, 1, 2.

P(no ‘4’) = P(Y = 0) = `25/36`

P(one ‘4’) = P(Y = 1) = `10/36`

P(two ‘4’) = P(Y = 2) = `1/36`

Probability mass function

y012
P(Y = y)25/3610/361/36

Now, we are going to find the cumulative probability distribution function

Formula:  `F(x) = sum_(x_i = -oo)^x P(X = x_i)`

Y = 0, F(0) = P(Y = 0) = 25/36

Y = 1, `F(1) = sum_(i = -oo)^1 P(Y = y_i)`

                = P(Y = 0) + P(Y = 1)

                = `25/36 + 10/36`

                = `35/36`

Y = 2, `F(2) = sum_(i = -oo)^2 P(Y = y_i)`

                = P(Y = 0) + P(Y = 1) + P(Y = 2)

                = `25/36 + 10/36 + 1/36`

                = `36/36`

                = 1

Cumulative distribution function

y012
F(Y)25/3635/361

Answer:

Probability mass function

y012
P(Y = y)25/3610/361/36

Cumulative distribution function

y012
F(Y)25/3635/361

Practicing Problems – Solve Cumulative Probability Distribution Function

Practicing problem 1

Find the cumulative distribution function for the given probability mass function

y0123
P(Y = y)2a4a6a8a

Find the value of a and `P(Y lt= 3)`

Answer:

The value of a is `1/20`

`P(Y lt= 3) = 1`

Practicing problem 2

Find the cumulative distribution function for getting number of heads when three coins are tossed once.

Answer:

Cumulative distribution function

y0123
F(y)1/81/27/81

Friday, January 25, 2013

Triangle Geometry Cosine

Look at this geometry figure:



In all these right angled triangles of different sizes, <A has the same measure. Since <B = 90o, we have <C = 90o - <A, in each of these triangles. So, all these triangles have equal angles and hence are similar. Thus even though the lengths of the sides BC, CA, AB are different in these, the numbers `(BC)/(AC)` and `(AB)/(AC)` are the same for all these triangles.

In all these triangles, AC is the hypotenuse. The side BC is the opposite side of <A. The third side AB is called the adjacent side of<A.    In a right angled triangle with <A as one of its angles, the number obtained by dividing the adjacent side of  <A by the hypotenuse is called the cosine of <A and its written cos A. Thus

cos A = `(adjacent- side- of- angleA) / ( hypotenuse )`

Note that cos A is a number indicating the size of <A alone and not depend on the size of the right angled triangle containing <A.

Examples for Triangle Geometry Cosine:

Example 1:

Determine the cosine of angle A or cos A; If <A =45o in the right angled triangle ABC, as in the figure below



then, as seen earlier, we have

`(BC)/(AC)` = `(AB )/(AC)` =1/`sqrt(2)`

which in our new terminology can be written

cos 45o = 1/`sqrt(2)`

Example 2:

Determine the cos30o, if <A =30o in the right angled triangle ABC, as in the figure below



Solution:

By definition, we know that   cos A = `(AB)/(AC)`

Therefore,   cos 30 = `sqrt(3)` / 2


Example 3:

Measure the cos C, if <C =60o in the right angled triangle ABC, as in the figure below





Solution:

Given:

`Delta` ABC , AB = `sqrt(3)` , BC = 1 and AC = 2.

To find the triangle geometry cosine C:

By definition, we know that,  cos C = `(BC)/(AC)`

That is                                     cos 60o = `1/2`

This is the required triangle geometry cosine values.

Example 4:

Measure the cosine of angle A or cos A; If <A =20o, AB = 4.7 and AC =5 in the right angled triangle ABC, as in the figure below



Solution:

Given:

In `Delta` ABC, <A = 20o , AB = 4.7 and AC =5.

To find the triangle geometry cosine of angle A:

We have found by actual measurement that in such a triangle as `Delta` ABC

`(AB)/(AC)` = `(4.7) /(5)`  = 0.94

This means in other words

cos 20o = 0.94