Question

Trig, Coterminal angles... Which of the following are coterminal with -pi/4 ... (a) 7pi/4 (b)3pi/4 (c)-5pi/4) (d)-9pi/4 (e) pi/4

Answer 1

Correct answers are a) and d)


`\alpha=- (\pi)/(4)`

Coterminal angles:
`\alpha+k\pi,\,k\in Z`


`- (\pi)/(4)+2\pi=- (\pi)/(4)+ (8\pi)/(4) = (7\pi)/(4) \\ \\- (\pi)/(4)-2\pi=- (\pi)/(4)- (8\pi)/(4) = -(9\pi)/(4)`