Question

given that cos theta equals -4/5 and the angle theta is in quadrant 2 find the value for sin theta

Answer 1

i love these...can I help?

Answer 2

First thing is, they tell you that theta is in the second quadrant. In the second quadrant, the x is negative and the y is positive, so let's draw out our angle using those facts.

Answer 3

In order to find the sin of theta, you need the side opposite the angle and the hypotenuse. You know the hypotenuse, it's 5, but the side opposite is x, so you need to find x. Use Pythagorean's theorem.

Answer 4

\[(5)^{2}-(-4)^{2}=x ^{2}\]\[25-16=x ^{2}\]\[9=x ^{2}\]\[3=x\]And x is positive because that value is positive in the second quadrant. So the sin of theta is

Answer 5

Oh I see it now. Thank you!