Question

WHERE IS MY MISTAKE?!?!?

Problem: Given that sinƟ = 2/3 and Π/2 < Ɵ < Π find the exact value of cosƟ

My solution:

cos^2(Ɵ) + sin^2(Ɵ) = 1

sin^2(Ɵ) = 1 - cos^2(Ɵ)
4/9=1- cos^2(Ɵ)
-5/9 = -cos^2(Ɵ)
5/9 = cos^2(Ɵ)
cos(Ɵ) = -sqrt(5/9)


Where is my mistake till now?

Answer 1

for one thing, the square root of 9 is 3

Answer 2

so if you were typing in an answer, it probably wanted it to look like
\[\cos(\theta)=-\frac{\sqrt{5}}{3}\]

Answer 3

other than that, it is all correct

Answer 4

@satellite73 So I didnt make any mistakes at all?

Answer 5

No.

Answer 6

@satellite73 confirm to me please if all of my steps above were correct, and even if they had a mistake which line?

Answer 7

just draw a triangle and with 0 = 2 and h = 3.. then find a then do a/h to get cos theta