Question #3ec3b

1 Answer
P dilip_k
Jan 8, 2018

#sec^2A+sec^2B=2#

#=>sec^2A-1+sec^2B-1=0#

#=>tan^2A+tan^2B=0#

Sum of two squared quantities being zero the possible real value if each should be zero.

Hence #tanA=0 and tanB=0#
This means

#A=npi " where "ninZZ#

And

#B=mpi " where "minZZ#

Now

#cos^5 A + sin^9 B#

#=cos^5 (npi) + sin^9 (npi)#

So possible values of the expression are #pm1#

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