2,5*19 - 9*2,5 - 0,25*31*4 = 47,5 - 22,5 - 31 = -6
Cosa=2/5
sina=√(1-cos²a)=√(1-4/25)=√(21/25)=√21/5
sin2a=2sinacosa=2*2/5*√21/5=4√21/25
cos2a=cos²a-sin²a=4/25-21/25=-17/25
tga=sina/cosa=√21/5:2/5=√21/5*5/2=√21/2
cos(π/3+a)=cosπ/3cosa-sinπ/3sina=1/2*2/5-√3/2*√21/5=1/5-3√7/10=(2-3√7)/10
sin(a-π/6)=sinacosπ/6-cosasinπ/6=√21/5*√3/2-2/5*1/2=3√7/10-1/5=(3√7-2)/10
Sin(Π/2+L)=cosL………… 2) ctg(360°-L)=-ctgL...... 3) sin(2Π+L)=sinL..... 4) tg(3Π/2-L)=ctgL.... 5) sin(270°-L)=-cosL
подставим координаты точки A(2;2)