NDA2020MathematicsTrigonometric Ratios & IdentitiesActual
Paragraph: Read the following information and answer: Let = =15^ . Question: What is ( +1^ )+ ( +1^ ) equal to?
Options
- A3 1^ + 1^
- B3 1^ - 1 2 1^
- C1 2 ( 3 1^ + 1^ )
- D1 2 ( 3 1^ + 1^ )
Correct answer
C. 1 2 ( 3 1^ + 1^ )
Step-by-step solution
( +1^ )+ ( +1^ )= 2 1 2 ( +1^ )+ 1 2 ( +1^ ) aligned = 2 45^ ( +1)+ 45^ ( +1) & & ( = ) aligned aligned & = 2 ( +1+45^ ) = 2 (15^ +1^ +45^ ) & = 2 61^ (i) aligned Again aligned & 1 2 ( 3 1^ + 1^ ) & = 2 2 ( 3 2 1^ + 1 2 1^ ) & = 2 ( 60^ 1^ + 60^ 1^ ) & = 2 ( 61^ ) (ii) & Thus ( i )=( ii ) aligned 1 2 ( 3 1^ + 1^ ) .