Question

the solution set of (5+4cos teta)(2cos teta+1)=0 in the interval (0,2pi)is



answer ​

Answer 1

Step-by-step explanation:

(5+4cosθ)(2cosθ+1)=0

⇒cosθ=−

4

5

(not possible) cosθ=−

2

1

⇒cosθ=−

2

1

⇒cosθ=−cos

3

π

⇒θ=

3

2π

,

3

4π

(II and III quad, cosine is negaitve)