Question

consider a right triangle with legs of length a and b and hypotenuse of length c if k denotes the area of the triangle then value of(a+b) equals

Answer 1

Area of a triangle is half the base times the height so:
0.5 x a x b = k

Hypotenuse we find using pythagaras:
a^2 + b^2 = c^2
c = sqrt(a^2+b^2)

Not sure what you mean by the value of (a+b). In terms of what?