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CBSE Class 10 Answered

How do you calculate the trigonometric ratios of 30(degrees) and 60(degrees)?
Asked by smjaanu | 05 Apr, 2009, 07:05: AM
answered-by-expert Expert Answer

Consider equilateral triangle ABC. Drop perpendicular AD onto BC.

We know that the perpendicular will bisect the base( has been proved in earlier classes)

So

BD=DC

and

Angle BAD=30  degrees

So, In right triangle ABD

 sin (Angle BAD)=sin 30 = opposite side / hypotenuse=BD/AB

=(a/2)/a=1/2.

Similarly , in the same triangle ratios of 60 degrees can be found.

(To find the length of AD , use pythagoras' theorem)

Answered by | 05 Apr, 2009, 09:06: AM

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