if A bar and B bar are vectors such that |A+B| = |A-B|, then the angle between A bar and B bar is
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Explanation:
Solution
Let a→,b→ are the two vectors .
Sum of vectors
=a¯+b¯=a2+b2+2abcosθ−−−−−−−−−−−−−−−√
Difference of vectors
=a¯−b¯=a2+b2−2abcosθ−−−−−−−−−−−−−−−√
Given ∣∣a¯+b¯∣∣=∣∣a¯−b¯∣∣
⇒a2+b2+2abcosθ−−−−−−−−−−−−−−−√
=a2+b2−2abcosθ−−−−−−−−−−−−−−−√
by squaring on both sides ,
a2+b2+2abcosθ=a2+b2−2abcosθ
∴ 4 ab cos θ=0 or θ=90∘
So if ∣∣a¯+b¯∣∣=∣∣a¯−b¯∣∣ then angle between a¯ and b¯is90∘ .
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