If , prove that , where is the angle between and…

MATHEMATICS · Subjective · CBSE · Mathematics · Vector Algebra · Vector Algebra

Problem

If ∣a∣=∣b∣=a\lvert\mathbf{a}\rvert=\lvert\mathbf{b}\rvert=a, prove that ∣a+b∣=2acos⁡θ2\lvert\mathbf{a}+\mathbf{b}\rvert=2a\cos\frac{\theta}{2}, where θ\theta is the angle between a\mathbf{a} and b\mathbf{b}.

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