find the value of sin30 geometrically

Hi!
Here is the answer to your question.
 
Consider an equilateral ∆ABC with sides AB = BC = CA = 2a.
 
 
 
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  • 37

Hello,

For finding the value of sin 300 geometrically, we construct an equilateral triangle ABC  of side 2 a. From A, we draw perpendicular AD to BC. Now, BD = CD  = 1/2 BC = a

In triangle ABD, BAD + BDA + DAB  = 180 (BY ANGLE SUM PROPERTY)

===> 600+ BAD + 90 0 = 180   (SINCE AD | BC  AND ALL ANGLES ARE 60  0  in a equilateral triangle)

===> BAD = 30 0

IN RT TRIANGLE BAD,

SIN 30  =  BD / AB=  a / 2 a   = 1/ 2

hence geometrically shown that sin 30 is 1/2

plz. answer my maths and chemistry question........

  • 59
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