Find the solution
2cos2x-2cosx=0

x = 0, 2π/3, 4π/3

Step-by-step explanation:

2 cos(2x) − 2 cos x = 0

Use double angle formula.

2 (2 cos²x − 1) − 2 cos x = 0

Simplify.

4 cos²x − 2 − 2 cos x = 0

2 cos²x − 1 − cos x = 0

2 cos²x − cos x − 1 = 0

Factor.

(cos x − 1) (2 cos x + 1) = 0

Solve.

cos x = 1 or -½

x = 0, 2π/3, 4π/3

question

what is the value of the third quartile of the data set represented by this box plot? a. 19 b. 21 c. 26 d. 29

answer

c