Poonam Dubey
Last Activity: 7 Years ago
It will be 90 degrees. Take the square of modulus of a+b and a-b separately. Since p and q are equal so there square will be obviously equal.now you may equate the whole square values of a+b and a-b and obtain the correct answer.A^2+B^2+2ABcos @=A^2+B^2-2ABcos@So 4ABcos@=0So, @=90° answer.