Start by multiplying to eliminate the parentheses:
You always want to look for cos^2 x + sin^2 x = 1, which, rearranged, is sin^2 x = 1 – cos^2 x.
This relationship is really just a variation of the Pythagorean theorem. The test makers love this
identity—it turns up a lot, so keep your eye out for it.
Here you can use the identity by substituting sin^2 x for 1 – cos^2 x:
The answer is (B).
For Math 2 you have to know a lot more than just SOHCAHTOA and “sin^2 x + cos^2 x = 1.” To begin
with, you’re supposed to know the other three trigonometric functions: cotangent, secant, and
cosecant. Like the three basic functions (sine, cosine, and tangent), these other three functions can
be defined in terms of “opposite,” “adjacent,” and “hypotenuse.” They can also be defined as
reciprocals of the three basic functions.
LEVEL 2 STRATEGY
Most angle measures on the Level 2 test are in degrees, but sometimes they’re in radians, so
read the questions carefully and switch your calculator to radian mode when appropriate.