Chapter 3 CNC Math 63
Trigonometric Functions
Since there are three sides (legs) to a triangle, there exist six different
ratios of sides. These ratios are the six trigonometric functions of sine,
cosine, tangent, cotangent, secant, and cosecant. Each ratio is named from
its relationship to one of the acute angle in a right triangle. The right angle is
never used in calculating functions. A function is obtained by dividing the
length of one side by the length of one of the other sides. These functions can
be found in math texts and many references, such as Machinery′s Handbook.
Special books also exist that give primarily trigonometric tables and values.
In addition, many calculators can compute trigonometric values. Figure 3-20
is a partial table of trigonometric functions covering 33°. To find the cosine
of 33°58′ , read down the minute column to 58 minutes, then read across
the row. Under the column labeled cosine, you find value 0.82936, which is
cosine 33°58′.
d
B
A
E
B B
A A
E E
Figure 3-19. As Line A increases in
length to become Line E, Angle d
increases in value, when Line B
remains the same.