TRIGONOMETRY
There are only 4
trigonometry questions on the ACT and they require a minimal knowledge of
trigonometry. You need to know the
following identity
and the six
trigonometric ratios.
|
Ratio |
Description |
|
sine |
|
|
cosine |
|
|
tangent |
|
|
secant |
|
|
cosecant |
|
|
cotangent |
|
|
a is the side
opposite a b is the side
adjacent a c is the
hypotenuse |
|
|
Example:
Find the sine, cosine, and tangent of a in the triangle at the right. sin a = 3/5 cos a = 4/5 tan a = 3/4 |
|
|
Example:
If sin a = and tana = Answer: Solution: tan a = sin a /cos a Þ cos a = = ( |
|
, find cos a.
)(
) = 
Example:
Simplify (1- cos x)(1 + cos x)
Answer: (1- cos
x)(1 + cos x) = 1 - 
Since = 
,
Example:
Simplify 
Answer: 
= 
= 
= cos x