COMEDK2022MathematicsTrigonometric Ratios & Identities
If A+ B=a and A+ B=b , then (A+B) equals?
Options
- Aa^2+b^2 b^2-a^2
- B2 a b a^2+b^2
- Cb^2-a^2 a^2+b^2
- Da^2-b^2 a^2+b^2
Correct answer
C. b^2-a^2 a^2+b^2
Step-by-step solution
Given A + B = a and A + B = b . Squaring both equations: ( A + B)^2 = a^2 ^2 A + ^2 B + 2 A B = a^2 ( A + B)^2 = b^2 ^2 A + ^2 B + 2 A B = b^2 Adding the two squared equations: ( ^2 A + ^2 A) + ( ^2 B + ^2 B) + 2( A B + A B) = a^2 + b^2 1 + 1 + 2 (A - B) = a^2 + b^2 2 (A - B) = a^2 + b^2 - 2 Subtracting the squared equations ( b^2 - a^2 ): b^2 - a^2 = ( ^2 A + ^2 B + 2 A B) - ( ^2 A + ^2 B + 2 A B) b^2 - a^2 = ( ^2 A - ^2 A) + ( ^2 B - ^2 B) + 2( A B - A B) b^2 - a^2 = 2A + 2B + 2 (A + B) b^2 - a^2 = 2 (A + B) (A -