the sum of magnitudes of two forces acting at a point is 18n and the magnitude of their resultant is 12n. if the resultant makes an angle of 90 degree with the force of smaller magnitude,what are the magnitude of two forces

Answer 1

Draw right triangle ABC with right angle at A.

As sides of the triangle, a^2 = b^2+c^2

a^2 = 12^2 + (18-a)^2
a = 13

You have a 5-12-13 triangle.