SOLUTION: Heres the question in the book: . Find the exact value of the following expression. Do not use a calculator. sin105cos15 Any help with this would be much appreciated.

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Question 205342: Heres the question in the book:
. Find the exact value of the following expression. Do not
use a calculator.
sin105cos15
Any help with this would be much appreciated.

Answer by stanbon(48558) (Show Source):
You can put this solution on YOUR website!
Find the exact value of the following expression. Do not
use a calculator.
sin105cos15
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105 = 60+45
15 = 60-45
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Your Problem becomes
sin(60+45)*cos(60-45)
= (sin60cos45-sin45cos60)(cos60cos45-sin50sin45)
-----------
Now put in the values and do the arithmetic.
--------------
Cheers,
Stan H.