Question

sin18°×cos36°=? вычислить

Answer 1

(sin18*cos18*cos36)/cos18=sin36*cos36/(2cos18)=sin72/(4cos18)=
=sin(90-18)/(4cos18)=cos18/(4cos18)=1/4=0,25

Answer 2

$\frac{(sin18*cos18*cos36)}{cos18} = sin36* \frac{cos36}{2cos18} = \frac{sin72}{cos18} = \\ \\ = \frac{sin(90-18)}{4cos18} = \frac{cos18}{4cos18} = \frac{1}{4} = 1:4 = 0,25 \\ \\ \\ OTBET: 0,25$