Question

calculaţi (cos 120°+cos 60°)(sin 135°-sin 45°)​

Answer 1

cos 120° =

cos 2π/3 =

cos(π-π/3) =

cos π · cos π/3 + sin π · sin π/3 = -1/2 + 0 = -1/2

sin 135° =

sin 3π/4 =

sin(π - π/4) =

sin π · cos π/4 - cos π · sin π/4 = 0 - (-1 ·√2/2) = √2 / 2

(cos120°+cos60°) (sin135°-sin45°) =

(-1/2 + 1/2) (√2/2-√2/2) = 0

Answer 2

Răspuns:

0

Explicație pas cu pas:

cum sin135°=sin(180°-45°)=sin45°, adoua paranteza este 0,, deci tot produsul este 0

as sin ple as that!!