**MACHINE SHOP CALCULATION - OD1640 - LESSON 2/TASK 3**

using tables 6 and 7 on pages 59 and 60 to find the angle of

the

corresponding function, as explained in the following two paragraphs.

b.

When the heading is at the top of the column, the number of degrees is

found at the top of the page, and the number of minutes will be in the

extreme left-hand column. In this case, the angle of the sine of .69466 is

44,, 0'.

c.

When the beading is at the bottom of the column, the number of degrees

is found at the bottom of the page, and the number of minutes will be in the

extreme right-hand column. NOTE: The following summary is provided to help

in locating the value of functions in the trigonometric tables.

This

summary shows how the functions of an angle change in value for angles from

0,, to 90,,. Notice that as the angle for sine increases from 0,, to 90,,, its

value also increases from zero to 1.0000. As the angle for cosine increases

from 0,, to 90,,, its value decreases from 1.000 to zero. As the angle for

tangent increases from 0,, to 90,,, its value increases from zero to infinity.

And, as the angle for cotangent increases from 0,, to 90,,, its value

decreases from infinity to zero.

EXAMPLE

Find the value of angle A when sin A = .96923.

SOLUTION

By referring to the preceding summary, it is seen that angle A must be

greater than 45,, and closer to 90,,. Therefore, examining the columns with

the sine heading at the bottom discloses the number

**65**