Precalculus help

[Smish0688]

Hello I am confused about a couple of problems I had on my last exam in precalculus class. One is cos x/2. It has to solved using the half angle formula. Another is sin^4 x
The last one is sin4x=root3/2
Can anyone help me solve these 3 problems? Thank you

 

[Deleted member 4993]

Hello I am confused about a couple of problems I had on my last exam in precalculus class. One is cos x/2. It has to solved using the half angle formula. Another is sin^4 x
The last one is sin4x=root3/2
Can anyone help me solve these 3 problems? Thank you

Please post the EXACT problem statements.

As posted - two of those do not make sense.

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Please show us what you have tried and exactly where you are stuck.

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[nasi112]

I don't know what you want exactly, but I will try to give you some hints and I hope that they can help you.

You have two ways to find [MATH]\cos \frac{x}{2}[/MATH][MATH]\cos^2 \frac{x}{4} = \frac{1}{2} \ (1 + \cos \frac{x}{2})[/MATH]
solve for [MATH]\cos \frac{x}{2}[/MATH]
another way is
[MATH]\sin^2 \frac{x}{4} = \frac{1}{2} \ (1 - \cos \frac{x}{2})[/MATH]
Now
[MATH]\sin^4 x = (\sin^2 x)^2 = (\frac{1}{2}(1 - \cos 2x))^2[/MATH]I think you got the idea and you can continue from here.

[MATH]\sin 4x = \frac{\sqrt{3}}{2}[/MATH]What do you want in here? To find the value of x?