Question

Find area of a triangle formed by lines y-x=0, x+y=0 and x-k=0.?

Answer 1

lines x-y=0 and x+y=0 are ⊥ to each other. k is the base. thus triagnle is right angled isoceles .
area of an isoceles right angled triangle= hypotenuse^2/4=k^2/4