Question

Find sine or cosine using identity

Answer 1

sin(theta) =
`(√(7))/(4)`

Explanation:

cos(theta) =
`(x)/(r)`

cos(theta) =
`(3)/(4)`

so x = 3 , r = 4 , and y =?

Pythagorean Theorem: x^2 +y^2 = r^2 or a^2 +b^2 = c^2

x^2 +y^2 = r^2

(3)^2 +y^2 = (4)^2

9 + y^2 = 16

y^2 = 7

`y=√(7),-√(7)`

In Quadrant 1, so its only
`y=√(7)`.

sin(theta) =
`(y)/(r)`

sin(theta) =
`(√(7))/(4)`