12./sin45° =x/sin(180° -45°)/2;
12√2 =x/cos45°/2 ;
12√2 =x/(√(1+cos45°)/2);
x=12√(1+cos45°) ;
x=6√(2(1+√2)) .
3/4, 1/2, 21/37, 7/8, 1/5, 6/11
24/576=24
140/1120=8
693/4851=7
648/5184=8
log₃ 72 -log₃ (16/27) +log₃ 18= log₃ 72 - log₃ 16 - log₃ 27 + log₃ 18=log₃(72/27)-log₃(16*18)=log₃(8/3)-log₃16+log₃18=log₃8-log₃3-log₃16+log₃18=log₃(8/16)-log₃3+log₃18=log₃(1/2)+log18-1=log₃1-log₃2+log₃18-1=0-log₃2+log₃18-1=log₃18-log₃2-1=log₃(18/2)-1=log₃9-1=2-1=1
Надо 80 * 40 получится 3200