Trigonometric proof for Pythagorean Identity : Sin^2θ + Cos^2θ = 1

There are three Pythagorean Identities with the first identity as:
Sin^2θ + Cos^2θ = 1. (Here, ^2 denotes "square" or "raised to power 2")
But how do we prove this identity by using Trigonometry?
This can also be stated as “sine of squared theta ” added to “cosine of squared theta” is one.

[vinodsareen]

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