(1+tanA.tanB)^2+(tanA-tanB) ^2= sec^2A. sec^2B
ICSE Class 10 Mathematics.
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Expand it n factorise it u will get d result
1+\tan ^{2}A*\tan ^{2}B+2\tan A\tan B+\tan ^{2}A+\tan ^{2}B-2\tan A\tan B=1+\tan ^{2}A+\tan ^{2}A*\tan ^{2}B+\tan ^{2}B=(1+\tan ^{2}A)(1+\tan ^{2}B)=\sec ^{2}A\sec ^{2}B
1+\tan ^{2}A*\tan ^{2}B+2\tan A\tan B+\tan ^{2}A+\tan ^{2}B-2\tan A\tan B=1+\tan ^{2}A+\tan ^{2}A*\tan ^{2}B+\tan ^{2}B=(1+\tan ^{2}A)(1+\tan ^{2}B)=\sec ^{2}A\sec ^{2}B
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