Question

(x-y) (x^2+y^2)(x^2+xy+y^2)(x^2-xy+y^2)(x^4-x^2y^2+y^4)​

Answer 1

Solve two equation :R

2

=9P

2

+4P

2

+12P

2

cosθ=13P

2

+12P

2

cosθ .....(1)

(2R)

2

=(2×3P)

2

+4P

2

+24P

2

cosθ=40P

2

+24P

2

cosθ ....(2)

Multiplying (1) by 4, 4R

2

=52P

2

+48P

2

cosθ .....(3)

Equating (2) and (3)

40P

2

+24P

2

cosθ=52P

2

+48P

2

cosθ

⇒12P

2

=−24P

2

cosθ

⇒cosθ=−

2

1

=cos120

∘

⇒θ=120

∘