9. Т.к. ∆RTK~∆ABC, то k = RT/AB. Тогда SRTK/SABC = k² = (RT/AB)² = (4/10)² = 16/100.
16/SABC = 16/100 => SABC = 100.
10. Т.к ∆ABC~∆A1B1C1, то AB/A1B1 = √(SABC/SA1B1C1) = k
4/x = √(32/50)
16/x² = 32/50
32x² = 16•50
2x² = 50
x² = 25.
x = 5.
11. Т.к. ∆MNT~∆M1N1T1, то k = x/9 = √(75/225)
x/9 = √(1/3)
x²/81 = 1/3
x² = 27
x = 3√3.