How do you solve 8\sin ^ { 2} \theta + 17\sin \theta + 9= 0?

1 Answer
Apr 27, 2017

theta=-90

Explanation:

Let sintheta=a

So we can write

8a^2+17a+9=0

or

8a^2+8a+9a+9=0

or

8a(a+1)+9(a+1)=0

or

(a+1)(8a+9)=0

or

a+1=0

or

a=-1

or

sintheta=-1

or

theta=-90--------Ans1

or

8a+9=0

or

8a=-9

or

a=-9/8

or

sintheta=-9/8

or

theta=Invalid

So we get theta=-90