Answer:
Step 1: Draw the vectors[Ref. Fig.]
Consider there are two vectors A and B such that B is perpendicular to the resultant R
Since the resultant is perpendicular to vector B we will get a right-angled triangle
Step 2: Equation formation
From the triangle
∣A∣2=∣B∣2+∣R∣2 ....(1)
Given , ∣R∣=∣A+B∣=12 ....(2)
∣A∣+∣B∣=18 ....(3)
Step 3: Solving Equations
Equation (3) and (1)⇒ ∣A∣2=(18−∣A∣)2+(12)2
⇒ ∣A∣2=182+∣A∣2−2×18∣A∣+
Explanation:
hope it helps
