NIMCET 2012 — Mathematics PYQ
NIMCET | Mathematics | 2012If A−B=4π, then (1+tanA)(1−tanB) is equal to:
Choose the correct answer:
- A.
2
(Correct Answer) - B.
1
- C.
0
- D.
3
2
Explanation
Step 1: Use the tangent subtraction formula
Given A−B=4π. Taking tan on both sides:
tan(A−B)=tan(4π)
1+tanAtanBtanA−tanB=1
Step 2: Rearrange the equation
tanA−tanB=1+tanAtanB
tanA−tanB−tanAtanB=1
Step 3: Evaluate the required expression
Expand the given expression:
(1+tanA)(1−tanB)=1−tanB+tanA−tanAtanB
Rearranging the terms:
1+(tanA−tanB−tanAtanB)
Step 4: Substitute the value from Step 2
From Step 2, we know that (tanA−tanB−tanAtanB)=1.
(1+tanA)(1−tanB)=1+1=2
Correct Option: (a)
Explanation
Step 1: Use the tangent subtraction formula
Given A−B=4π. Taking tan on both sides:
tan(A−B)=tan(4π)
1+tanAtanBtanA−tanB=1
Step 2: Rearrange the equation
tanA−tanB=1+tanAtanB
tanA−tanB−tanAtanB=1
Step 3: Evaluate the required expression
Expand the given expression:
(1+tanA)(1−tanB)=1−tanB+tanA−tanAtanB
Rearranging the terms:
1+(tanA−tanB−tanAtanB)
Step 4: Substitute the value from Step 2
From Step 2, we know that (tanA−tanB−tanAtanB)=1.
(1+tanA)(1−tanB)=1+1=2
Correct Option: (a)

