Question

*URGENTE* Se cos x=−4/5, e $180º\ \textless \ x\ \textless \ 270º$, qual é tan⁡(2x)?

Answer 1

senx=√1-cos²x=√1-(16/25)=√9/25= -3/5

tgx = senx/cosx = -3/5 / -4/5 = 3/4

tg2x= 2.tgx/1-tg²x

tg2x= 2.3/4 / 1-(9/16)

tg2x= 3/2 / 7/16

tg2x= 3/2 • 16/7 = 48/14 = 24/7 ✓