Question
Wed May 02, 2012 By: Venkatesh Sehgal
 

SIN SQUARE 5 DEGREE +SIN SQUARE 10 DEGREE +SIN SQUARE 15 DEGREE+...+SIN SQUARE 85 DEGREE+SIN SQUARE 90 DEGREE=?

Expert Reply
Thu May 03, 2012
sin25+sin210+sin215+......+sin290
= sin2(90-85)+sin2(90-80)+......+sin285+ sin290
= cos285+cos280+......+sin285+ sin290
= (sin285+cos285)+(sin280+cos280) +......(sin250+cos250)+sin245+ sin290
= 1+1+...8 times + 1/2 + 1
=9.5 Ans
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