1]If A = B+C and the magnitude of A, B and C are 5,4,3 unit, the angle between A and B is : (a)cos-13/5 (b) cos-14/5 (c)p/2 (d) sin-1 3/5

tan x= c sino/(b+ c coso)

on solving we get x= cos-1 4/5 or sin-1 3/5

A = B+C 

A-B = C , now squaring both sides

(A-B)² = C²

 A²+B²-2(A.B) = C²

    (A.B) = (25+16-9)/2 = 32/2                                (A.B(A dot B) = ABCOS@)

    ABCOS@ = 16

       COS@ = 4/5

     SIN@ = 3/5 OR @ = SIN^-3/5

OPTION D) IS CORRECT

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