Trigonometry
Angle Sum and Difference, Double Angle and Half Angle Formulas
Find the exact value of:
If sinx = 4/8, find Cos (6x)

3√3

Step-by-step explanation:

If sinx = 4/8, find Cos (6x)

we need to first find cos

but applying trigonometry rule

sin²x+cos²x = 1

sinx = 4/8

sin²x = (4/8)² = 4²/8² = 16/64

from the rule

cos²x= 1 -sin²x = 1-16/64 = 64-16/64 = 48/64 = 3/4

cos²x = 3/4

cos x = √3/4 = √3/2

cos 6x = 6 x √3/2 = 3√3

you can't solve x because it is 2 linear equation and you only have one equation