Question

question number 10

problem !! problem !! problem !!

need

solution !! solution !! solution !!

Answer 1

this may be the result a
or else take the magnitude of p.q

Answer 2

!! Hey Mate !!

your answer is --

Given,

A = 2i^ + 3j^ and B = i^ - 2j^

Now,

A+B = 2i^+3j^+i^-2j^ = 3i^ + j^ = C (say)

A-B = 2i^+3j^-i^+2j^ = i^ + 5j^ = D (say)

Now, magnitude of A+B or C is

$\sqrt{ {3}^{2} + {1}^{2} } = \sqrt{10}$

and magnitude of A-B or D is

$\sqrt{ {1}^{2} + {5}^{2} } = \sqrt{26}$
Let , angle between C and D is @

Now , Take dot product of C and D , we get

C.D = CD cos@

=> (3i^+j^).(i^+5j^) = √10 × √26 cos@

=> ( 3×1+1×5) = √260 cos@

=> 8 = √260 cos@

=> 8 = 2√65 cos@

=> cos@ = 4/√65

=> @ = cos^-1(4/√65)

Hence, required angle is cos^-1(4/√65)


【 Hope it helps you 】