## Prove that Sin squared theta + Cos squared theta is equal to 1

We know that;

Sin theta=Perpendicular/Hypotenuse=P/H=a/c

Cos theta=Base/Hypotenuse=B/H=b/c

So, Sin^2 theta+Cos^2 theta=a^2/c^2+b^2/c^2=a^2+b^2/c^2 …….(i)

By Pythagoras Theorem, in a right-angled triangle:

Hypotenuse^2=Base^2+Perpendicular^2

c^2=a^2+b^2

1=a^2+b^2/c^2………(ii)

Put eq. (ii) in eq. (i), we get

Sin^2 theta+Cos^2 theta = 1

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