1)<span>Берешь длину отрезка АБ и вычитаешь из его известные кусочки </span>
<span>Нарисуй задачку на бумаге и сама увидишь как все просто.
2)</span>сумма смежных углов=180⁰
пусть х-первый угол,тогда х+20-второй.
х+х+20=180
2х=160
х=80⁰-первый угол.
<span>а)80⁰+20⁰=100⁰-второй угол.
3)Вариант 1:
</span>< ВОД = < СОА -----вертикальные углы
Пусть < СОА = x
Тогда < АОК = 118 -x
< COA + < AOK = 180
x + (118 -x) + (118-x) = 180
<span>x = 56 градусов--- это и есть угол ВОД
</span>Вариант 2:
Обозначь углы AOK и KOD за х, а угол COB за 2х
COD-KOD=COK
180-х=118
Х=62
COD-COB=BOD
180-(62•2)=56
6х-7x>5-2
-x>3
x>3:(-1)
x<-3
<span>f′(x)=<span><span>(<span><span>sin<span>(x)</span>+cos<span>(x)/</span></span><span>sin<span>(x)</span>−cos<span>(x)</span></span></span>)</span>′</span>=</span><span><span>=<span><span><span><span>(<span>sin<span>(x)</span>+cos<span>(x)</span></span>)</span>′</span>⋅<span>(<span>sin<span>(x)</span>−cos<span>(x)</span></span>)</span>−<span>(<span>sin<span>(x)</span>+cos<span>(x)</span></span>)</span>⋅<span><span>(<span>sin<span>(x)</span>−cos<span>(x)</span></span>)</span>′/</span></span><span><span>(<span>sin<span>(x)</span>−cos<span>(x)</span></span>)^</span>2</span></span></span>=</span><span>=<span><span><span><span>(<span><span><span>(<span>sin<span>(x)</span></span>)</span>′</span>+<span><span>(<span>cos<span>(x)</span></span>)</span>′</span></span>)</span>⋅<span>(<span>sin<span>(x)</span>−cos<span>(x)</span></span>)</span>−<span>(<span>sin<span>(x)</span>+cos<span>(x)</span></span>)</span></span><span>⋅<span>(<span><span><span>(<span>sin<span>(x)</span></span>)</span>′</span>−<span><span>(<span>cos<span>(x)</span></span>)</span>′</span></span>)/</span></span></span><span><span>(<span>sin<span>(x)</span>−cos<span>(x)</span></span>)^</span>2</span></span>=</span><span>=<span><span><span><span>(<span>cos<span>(x)</span>+<span>(<span>−sin<span>(x)</span></span>)</span></span>)</span>⋅<span>(<span>sin<span>(x)</span>−cos<span>(x)</span></span>)</span>−<span>(<span>sin<span>(x)</span>+cos<span>(x)</span></span>)</span></span><span>⋅<span>(<span>cos<span>(x)</span>−<span>(<span>−sin<span>(x)</span></span>)</span></span>)/</span></span></span><span><span>(<span>sin<span>(x)</span>−cos<span>(x)</span></span>)^</span><span>2</span></span></span></span>
1.
а)2,8-3,1-4,9+4,2=7-8=-1
б)0,3*2/7+0,3*5/7=0,3*(2/7+5/7)=0,3*1=0,3
2.
А)2х+3=0
2х=-3
х=-3/2
х= -1,5
б)6х-7=15+2х
6х-2х=15+7
4х=22
х=22/4
х=5,5
4.
4(4с-3)-(10с+8)=16с-12-10с-8=6с-20
Если с=5/6, то
30/6-20=5-20= -15
