(2sin35.sin55)/cos20=2.sin35.cos35/cos20=
=sin70/cos20=sin70/sin70=1
(sin2x=2.sinx.cosx, sin(90-x)=cosx, cos(90-x)=sinx)
tg35.tg55=sin35/cos35 . sin55/cos55=(sin35.sin55)/(cos35.cos55)=
=(sin35.sin55)/(sin55.sin35)=1
(tgx = sinx/cosx, cos35=sin(90-35)=sin55,cos55=sin(90-55)=sin35)
Решение
- 3х + 9y = - 15
3x - 9y = 15
0 = 0
Любые значения переменных Х и y
Три решения :
( 0 ; 0 ) ; ( 1 ; 1 ) ; ( 5 ; 5 )
Y=2sinx E(y)=[-1;1]
y=2sinx+1 E(y)=[0,2]
1)
2) (3³)² = 3⁶ = 729
3) 0,5² * 2¹² = (1/2)² * 2¹² = (2⁻¹)² * 2¹² = 2⁻² * 2¹² = 2⁻²⁺¹² = 2¹⁰ = 1024
4) (3⁴)⁵ : 3¹⁹ = 3²⁰ : 3¹⁹ = 3²⁰⁻¹⁹ = 3¹ = 3