NDA2018MathematicsTrigonometric Ratios & IdentitiesActual
If A + B + C =180^ , then what is 2 ~A - 2 ~B - 2 C equal to?
Options
- A-4 ~A ~B C
- B-4 ~A ~B C
- C-4 ~A ~B C
- D-4 A B C
Correct answer
D. -4 A B C
Step-by-step solution
aligned & 2 A- 2 B- 2 C & =2 (A+B) (A-B)+ (2 A+2 B) & =2 (A+B) (A-B)+2 (A+B) (A+B) & =2 (A+B)[ (A-B)+ (A+B)] & =-2 C 2 A B] & =-4 A B C aligned