if you don't have a Unit Circle yet, this is a good time to get one, you can find many online, check maybe in yahoo images, or google images.
Check the picture below.
notice the section encircled in purple.
:
Since
, we get:

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We have
simplify 
then the radical rule is used: ![\quad \sqrt[n]{ab}=\sqrt[n]{a}\sqrt[n]{b}](https://tex.z-dn.net/?f=%5Cquad%20%5Csqrt%5Bn%5D%7Bab%7D%3D%5Csqrt%5Bn%5D%7Ba%7D%5Csqrt%5Bn%5D%7Bb%7D)
⇒ 
Now we have
and 

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and 

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since
is the half of 
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<em>(-4+5=1)</em>
Answer:
these triangles some is 90°.
72°+2x=90°
2x=90°-72
2x=18
x=18/2
x=9
I don’t know the answer to this bc I can’t remember
Is there a picture of some sort of angle or parallelogram? Because there isn't enough information to solve the question with only this. Sorry!