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Question: If \(A + B = \frac{\pi}{4},\) then \((1 + \tan A)(1 + \tan B) =\)...

If A+B=π4,A + B = \frac{\pi}{4}, then (1+tanA)(1+tanB)=(1 + \tan A)(1 + \tan B) =

A

1

B

2

C

\infty

D

– 2

Answer

2

Explanation

Solution

Given that A+B=π4tan(A+B)=tanπ4A + B = \frac{\pi}{4} \Rightarrow \tan(A + B) = \tan\frac{\pi}{4}

tanA+tanB1tanAtanB=1\Rightarrow \frac{\tan A + \tan B}{1 - \tan A\tan B} = 1

tanA+tanB+tanAtanB=1\Rightarrow \tan A + \tan B + \tan A\tan B = 1

(1+tanA)(1+tanB)=2\Rightarrow (1 + \tan A)(1 + \tan B) = 2.