Р=2(а+в),пусть а-длина, тогда ширина в=а+5; 26=2(а+а+5); 2а+5=13; 2а=8; а=4-это длина,а ширина 4+5=9
SinA=0.25=1/4
c=4
a=BC=1
b=AC=√15
sinA=BC/AB=cosB=1/4=0.25
( - 1/7a3b4c2) ( 3 1/2a2bc3) = -1/7*7/1*a5b5c5 = -a5b5c5= -(abc)^(5)
(2m2 + 3/5n) (3/5n - 2m2) = 6/5m2n -4m4+9/25n2-6/5nm2=9/25n2-4m4=(3/5n-2m2)(3/5n+2m2)
<span>(18x3y3 - 12x4y) : (6x3y) = 6x3y(3y2-2x) / 6x3y = 3y2-2x</span>
<span>16 cos20 cos40 cos60 cos80=8 cos20cos40cos80=8cos20cos40cos80sin20/sin20=4sin40cos40cos80/sin20=2sin80cos80/sin20= sin160/sim20=sin(180-20)/sin20=sin20/sin20=1
соs60=1/2</span>