Question

Find the exact value of cos x, given that sin α = 4/7
and a is in quadrant II.
Cos=___

Answer 1

Since sin α = 4/7 and a is in quadrant II, we can use the Pythagorean identity to find cos α:

cos²α + sin²α = 1

cos²α = 1 - sin²α
= 1 - (4/7)²
= 1 - 16/49
= (49-16)/49
=33/49

Since a is in quadrant II, cos α will be negative. Therefore,

cos α = -√(33/49)
= -(√33)/7

So, the exact value of cos x is -(√33)/7.