Question

If costheta+sintheta=1,prove that costheta-sintheta=+-1

Answer 1

Heyy mate ❤✌✌❤

Here's your Answer....

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Using the formula

(a+b)2+(a−b)2=2(a2+b2)

(cosθ+sinθ)2+(cosθ−sinθ)2=2(sin2θ+cos2θ)

⇒12+(cosθ−sinθ)2=2×1

⇒(cosθ−sinθ)2=2−1=1

⇒cosθ−sinθ=±1
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