РЕШЕНИЕ:



a =4 и b =8

∆BCD ∞ ∆ CAD

BC = BD
AC _ CD

8x = 4 + 8 + y
4x _ CD

8 CD = 4 (12 + y)

2 CD = 12 + y

y = 2 CD – 12

CD² = AD ∙ BD

CD² = y ∙ (4 + 8 + y)

CD² = (2 CD – 12) ∙ (4 + 8 + 2 CD – 12)

CD² = (2 CD – 12) ∙ 2 CD

CD = (2 CD – 12) ∙ 2

CD = 4 CD – 24

4 CD – CD = 24

3 CD = 24

CD = 8

Ответ: 8

РЕШЕНИЕ:



a =5 и b =10

∆BCD ∞ ∆ CAD

BC = BD
AC _ CD

10x = 5 + 10 + y
5x _ CD

10 CD = 5 (15 + y)

2 CD = 15 + y

y = 2 CD – 15

CD² = AD ∙ BD

CD² = y ∙ (5 + 10 + y)

CD² = (2 CD – 15) ∙ (5 + 10 + 2 CD – 15)

CD² = (2 CD – 15) ∙ 2 CD

CD = (2 CD – 15) ∙ 2

CD = 4 CD – 30

4 CD – CD = 30

3 CD = 30

CD = 10

Ответ: 10