If vector P+vector Q=vector R ;and if P^2+Q^2=R^2 then find the angle between the vectorP and vectorQ?

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Answer 1 · 2018-02-18T06:21:34

#90^@#

Given, #vec P + vec Q=vec R#

So, we can write,

#|vec R| = sqrt(P^2+Q^2 +2PQ cos theta)#,where #theta# is the angle between the two vectors.

Or, #R^2 =P^2 + Q^2 +2PQ cos theta#

Given, #P^2 + Q^2 = R^2#

So, #R^2 = R^2 + 2PQ cos theta#

Or, #2PQ cos theta =0#

So, #cos theta =0#

Or, #theta =90^@#