(MAUÁ - 1977) Dada a equação $\phantom{X}(sen\,x\,+\,cos\,y)(sec\,x\,+\,cossec\,y)\,=\,4\phantom{X}$:
a) resolva-a se $\phantom{X}x\,=\,y\phantom{X}$
b) resolva-a se $\phantom{X}sen\,x\,=\,cos\,y\phantom{X}$
resposta:
a) x = y = π/4 + kπ b) x = π/4 + kπ e y + x = π/2 + 2kπ×