99 Percentile Qs Bank for JEE MainMathematicsTrigonometric Ratios & Identities
In a triangle ABC , with usual notations, if c =4 , then value of (a-b)^2 ^2 C 2 +(a+b)^2 ^2 C 2 is
Options
- A4
- B16
- C9
- D2
Correct answer
B. 16
Step-by-step solution
aligned & (a-b)^2 ^2 C 2 +(a+b)^2 ^2 C 2 & = (a^2-2 a b+b^2 ) ^2 C 2 + (a^2+2 a b+b^2 ) ^2 C 2 & = (a^2+b^2 ) ( ^2 C 2 + ^2 C 2 ) & -2 a b ^2 C 2 +2 a b ^2 C 2 & =a^2+b^2-2 a b ( ^2 C 2 - ^2 C 2 ) & =a^2+b^2-2 a b C & =a^2+b^2- (a^2+b^2-c^2 ) [ By Cosine rule ] & =c^2=4^2=16 aligned