inverse trigonometry
pls help me
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Answer:
tan^-(1/4) + tan^-1(2/9)
= tan^-1[ (1/4 + 2/9)/(1-(1/4)(2/9) ) ]
=tan^-1 [ ((9+8)/36) / (1-1/18) ]
=tan^-4 [ (17/36)/(17/18) ]
=tan^-1 [(1/2)]
by pythagoras c² = (1)² + 2² = 5
=> c = √5
=> cos^-1(2/√5)
hence... proved
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