Question

✯Brainly stars ✯Moderaters ✯Other best users! Q. How do you find the exact value of cos(theta) if sin(theta)= - 2/3? Explain. \sf \longrightarrow \red{ Don't \: spam}⟶Don ′ tspam Thanks! ^_^​

Answer 1

Answer:

Explanation:cos  

θ

=  

√

5

3

or it could be cos  

θ

=  

√

5

−

3

Explanation:

Since sin  

θ

is negative, it can be in the third or fourth quadrant

Drawing your right-angled triangle, place your  

θ

in one of three corners. Your longest side will be 3 and the side opposite the  

θ

will be -2. Finally, using Pythagoras theorem, your last side should be  

√

5

Now, if your triangle was in the third quadrant, you would have

cos  

θ

=  

√

5

−

3

since cosine is negative in the third quadrant

But if your triangle was in the fourth quadrant, you would have

cos  

θ

=  

√

5

3

since cosine is positive in the fourth quadrant