4 cos 15°*sin 15°<span> *sin 100</span>°<span>=
= 2*(2</span>cos 15°sin 15°)sin 100°=
= 2 sin 30°sin100°= 2* 1/2 sin100° = sin100°=
= sin(90°+10°) = cos10°
Пропорция:
17/40=x/25
x=25*17/40=5*17/8=10.625 км=10625м
9* cos (x)=sin (x)
tg (x)=9
x=arctg (9)+pi*k