# Math

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Without using calculator,evaluate Sin15 deg,Cos 15 deg,Sin 75deg. O need the answer urgently pls.

• Math -

sin 15°
= sin(45-30)
= sin45cos30 - cos45sin30
= (1/√2)(√3/2) - (1/√2)(1/2)
= (√3 - 1)/(2√2)

so cos 15° the same way

and for the last : sin(75°) = sin(45+30)

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