Proving identities

Prove that

cos theta / 2 = sqrt[1 + (cos theta / 2)]

I know this is somewhat similar to cosine - half of an angle identity or formula

But I'm having trouble with the division bar, it only divides cos theta not the whole 1 + cos theta. As a result, I can't prove it

Is (1 + cos theta ) / 2 the same to 1 + cos theta /2 ?

Please explain, thanks

Quote:

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Originally Posted by ImKo

Prove that

cos theta / 2 = sqrt[1 + (cos theta / 2)]

I know this is somewhat similar to cosine - half of an angle identity or formula

But I'm having trouble with the division bar, it only divides cos theta not the whole 1 + cos theta. As a result, I can't prove it

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Quote:

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Originally Posted by ImKo

Is (1 + cos theta ) / 2 the same to 1 + cos theta /2 ?

Please explain, thanks

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well, kabayan, it depends on the grouping. it will be helpful if group it properly..

but i think, this is what you wanted to prove..



if this is the case, use the indentity and let

Thanks Kabayan..

I think the book had just an error since the hint it gave is also the same as the one you gave me.