Question

If sinθ= 4/5 in quadrant II, what is cosθ?

Answer 1

cos theta = -3/5

Explanation:

Answer 2

Answer:
`cos\theta=-(3)/(5)`

Explanation:

`sin\theta = (y)/(r)=(4)/(5)`

Step 1: Use Pythagorean Theorem: x² + y² = r² to find the x-value

x² + 4² = 5²

x² + 16 = 25

x² = 9

x = 3

Step 2: Use the Quadrant to determine the sign of the x-value

Quadrant II Quadrant I

(--, +) (+, +)

Quadrant III Quadrant IV

(--, --) (+, --)

x is negative in Quadrant II

`cos\theta=(x)/(r)=\large\boxed{-(3)/(5)}`