tan 9A - tan 5A - tan 4A = tan 9A × tan 5A × tan 4A
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Answer:
Step-by-step explanation:
Tan9A=tan(5A+4A)
Using tan(a+b) formula
Tan 9A = tan5A+tan4A/ 1-tan5atan4a
Tab9A-tan9Atan5Atan4A=tab5a+tan4a
Thus
Tan 9A-tan4A-tan5A= tan9Ax tab5A x tan4A
Hence proved
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