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Daca 0 grade < x,y <90 grade, sin x=[tex] \frac{1}{3} [/tex] si cos x= [tex] \frac{1}{4} [/tex] , calculati 16tg²x+ 9tg²y.

Multumesc!


Răspuns :

Voi considera cos y=1/4, enuntul fiind gresit.
sin²x=1/9
cos²x=1-sin²x=1-1/9=8/9
cos²y=1/16
sin²y=1-1/16=15/16
16tg²x+ 9tg²y=16 sin²x/cos²x+9sin²y/cos²y=
=16·1/9·9/8+9·15/16·16/1=
=2+135=137