CUET PG 2022 — Mathematics PYQ
CUET PG | Mathematics | 2022If A + B = 45°, then (1+tanA)(1+tanB) is equal to
Choose the correct answer:
- A.
4
- B.
2
(Correct Answer) - C.
3
- D.
1
2
Explanation
Step 1: Use the Tangent Addition Formula
We are given:
A+B=45∘
Taking the tangent on both sides:
tan(A+B)=tan45∘
We know that tan45∘=1 and the expansion for tan(A+B) is:
1−tanAtanBtanA+tanB=1
Step 2: Rearrange the Equation
Cross-multiply to remove the fraction:
tanA+tanB=1−tanAtanB
Now, move the term −tanAtanB to the left side:
tanA+tanB+tanAtanB=1
Step 3: Expand the Required Expression
Now, let's expand the expression we need to evaluate:
(1+tanA)(1+tanB)=1+tanB+tanA+tanAtanB
Notice that the last three terms (tanA+tanB+tanAtanB) match the left side of our equation from Step 2.
Step 4: Substitute and Solve
From Step 2, we found that:
tanA+tanB+tanAtanB=1
Substitute this value into our expanded expression:
(1+tanA)(1+tanB)=1+(1)
(1+tanA)(1+tanB)=2

