Question

ajutati-ma va rog mult!

Answer 1

Răspuns:

Aplici formula

sin²a+cos²a=1
Inlocuiesti cosa cu-4/5

sin²a+(-4/5)²=1

sin²a+16/25=1

sin²a=1-16/25=9/25

sina=√9/25=±3/5

(-π,-π/2)-este cadranul 3 unde sinusul e negativ=>

sinx=-3/5

E(a)=4/5tga+5./12 sin 2a=

4/5 sina/cosa+5/12 *2sin*cos A=

4/5(-3/5)/(-4/5)+5/6*(-3/5)*(-4/5)=

3/5+5/6*12/25=

3/5+2/5=5/5=1

-3/3

48/125+2/25=

48/125+10/125=58/125

Explicație pas cu pas: