+0

# Help?

0
147
1

What is the value of sin θ, given that cosθ=-2/5 and sin θ>0

Guest Apr 14, 2017

#1
+5552
+2

If cosθ = -2/5 and sin θ > 0, this is the triangle ∠θ makes:

Use the Pythagorean theorem to find sin θ .

(-2/5)2 + sin2 θ = 12

sin2 θ = 1 - (-2/5)2

Take the + square root of both sides.

sin θ =  $$+\sqrt{1-(-2/5)^2}=\sqrt{1-\frac4{25}}=\sqrt{\frac{21}{25}}= \frac{\sqrt{21}}{5}$$

hectictar  Apr 14, 2017
Sort:

#1
+5552
+2

If cosθ = -2/5 and sin θ > 0, this is the triangle ∠θ makes:

Use the Pythagorean theorem to find sin θ .

(-2/5)2 + sin2 θ = 12

sin2 θ = 1 - (-2/5)2

Take the + square root of both sides.

sin θ =  $$+\sqrt{1-(-2/5)^2}=\sqrt{1-\frac4{25}}=\sqrt{\frac{21}{25}}= \frac{\sqrt{21}}{5}$$

hectictar  Apr 14, 2017

### 3 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details