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Question: \[\mathbf{\tan}\mathbf{1}\mathbf{00}\mathbf{{^\circ}}\mathbf{+}\mathbf{\tan}\mathbf{1}\mathbf{25}\ma...

tan100+tan125+tan100tan125=\mathbf{\tan}\mathbf{1}\mathbf{00}\mathbf{{^\circ}}\mathbf{+}\mathbf{\tan}\mathbf{1}\mathbf{25}\mathbf{{^\circ}}\mathbf{+}\mathbf{\tan}\mathbf{1}\mathbf{00}\mathbf{{^\circ}}\mathbf{\tan}\mathbf{1}\mathbf{25}\mathbf{{^\circ}}\mathbf{=}

A

0

B

1/2

C

– 1

D

1

Answer

1

Explanation

Solution

tan(100o+125o)=tan100o+tan125o1tan100otan125o\tan(100^{o} + 125^{o}) = \frac{\tan 100^{o} + \tan 125^{o}}{1 - \tan 100^{o}\tan 125^{o}}

\therefore tan225o=tan100o+tan125o1tan100otan125o\tan 225^{o} = \frac{\tan 100^{o} + \tan 125^{o}}{1 - \tan 100^{o}\tan 125^{o}}

i.e., 1=tan100o+tan125o1tan100otan125o1 = \frac{\tan 100^{o} + \tan 125^{o}}{1 - \tan 100^{o}\tan 125^{o}}

i.e.,tan100o+tan125o+tan100otan125o=1.\tan 100^{o} + \tan 125^{o} + \tan 100^{o}\tan 125^{o} = 1.