Originally Posted by

**mrjameslat** Ok I don't understand how to do these 3 types of questions.

Please help me** understand **how to do them. Thanks for your time.

1. Verify the identity (Can only change one side, and end result must equal each other)

cos^3Xsin^2X=(sin^2X-sin^4X)cosX

left side ... cosx(cos^2x sin^2x) = cosx[(1 - sin^2x)sin^2x] = cosx(sin^2x - sin^4x)

2. Sole the equation.

4cosX=1+2cosX

subtract 2cosx from both sides ...

2cosx = 1

cosx = 1/2 ... x = pi/3, x = 5pi/3

3. Find the exact values of the sine, cosine, and tangent of the angle by using the sum or difference formula.

345 degrees = 300 degrees + 45 degrees

use the sum/difference identities ...

cos(a+b) = cosa cosb - sina sinb

sin(a+b) = sina cosb + cosa sinb

tan(a+b) = (tana + tanb)/(1 - tana tanb)