Sina*cosa*cosa/sina -1=cos²a-1=-sin²a
1) равно 660
2) равно 793
<span>7,5 *(8.1/2 - 8,18)=7,5*(17/2-8,18)=7,5*(8,5-8,18)=7,5*(0,32)=2,4
----------------------------------------------------------------------------------------------- =2
</span>
<span>(9,5 - 7.2/5) *4/7
= (21/10) * 4/7 = 6/5 =1 1/5 = 1.2</span>
2/3=0,667
6/7=0,857
2/13=0,154
5/19=0,263