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I need help solving this problem I’m struggling to answer it. It is trigonometry and it is from my ACT prep guide

I need help solving this problem I’m struggling to answer it. It is trigonometry and-example-1
User Zoneur
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2.3k points

1 Answer

10 votes
10 votes

The Solution:

Given the value below:


\cos \lbrack\sin ^(-1)(-0.845)\rbrack

We are asked to find the value of the above expression rounded to the nearest thousandth.

So, applying the property rule:


\sin ^(-1)(-x)=-\sin ^(-1)(x)

We have that:


\sin ^(-1)(-0.845)=-\sin ^(-1)(0.845)=-57.671936

So, it follows that:


\cos \lbrack\sin ^(-1)(-0.845)\rbrack=\cos (-57.671936)

Applying the property rule:


\cos (-x)=\cos (x_{})

We have that:


\cos \lbrack\sin ^(-1)(-0.845)\rbrack=\cos (-57.671936)=\cos (57.671936)=0.534766

Rounding to the nearest thousandth, we get


\cos \lbrack\sin ^(-1)(-0.845)\rbrack=\cos (-57.671936)=0.534766\approx0.535

Therefore, the correct answer is 0.535

User Gansub
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