3) x^2 = 5^2 + 1^2 = 26
x = sqrt (26)
y^2 = 12^2+5^2 = 144 + 25 = 169
y = 13
4) y^2 = 8^2 + 10^2 = 64 + 100 = 164
y = 2*sqrt (41)
(x+8)^2 + 10^2 = 26^2
x^2 + 16x + 64 + 100 = 676
x^2 + 16x - 512 = 0
D = 256 - 4*(-512) = 2304 = 48^2
x1 = (-16+48)/2 = 16
x2 <0 не удовл.<br>
5) x^2 = 10^2 - 8^2 = 36
x = 6
6) 15^2 = 9x^2 + 16x^2 = 25x^2
x^2 = 9
x = 3
x = -3 не подх.
7) (x+3)^2+x^2 = 15^2
x^2+6x+9+x^2 = 225
2x^2+6x-216 = 0
x^2 + 3x - 108 = 0
D = 9-4*(-108) = 441
x1 = (-3+21)/2 = 9
x2 <0 не подх.<br>
8) 169x^2= 25x^2 + 576
144x^2 = 576
x^2 = 4
x= 2
9) по усл. один угол = 45°, второй =90, значит, третий = 180 - 90 - 45 = 45, то есть x=y
2x^2=400
x^2=200
x=10*sqrt (2)