If cos 0 + sin 0 = √2 cos q, then show that cos 0 - sin 0 =√2
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Answer:
Step-by-step explanation:
Cosθ + Sinθ = √2 Cosθ
Squaring both sides
=> Cos²θ + Sin²θ + 2CosθSinθ = 2Cos²θ
=> 2CosθSinθ = Cos²θ - Sin²θ
Cos² + Sin²θ = 1
Subtracting 2CosθSinθ from both sides
=> Cos² + Sin²θ - 2CosθSinθ = 1 - 2CosθSinθ
=> (Cosθ - Sinθ)² = 1 - 2CosθSinθ
using 2CosθSinθ = Cos²θ - Sin²θ
=> (Cosθ - Sinθ)² = 1 - (Cos²θ - Sin²θ)
=> (Cosθ - Sinθ)² = 1 - Cos²θ + Sin²θ
=> (Cosθ - Sinθ)² = Sin²θ + Sin²θ
=> (Cosθ - Sinθ)² = 2Sin²θ
=> Cosθ - Sinθ = √2 Sinθ
QED
Proved
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