Answer:
17.5
Step-by-step explanation:
90% sure
Answer:
By hypotenuse - side test (HL) the two triangles are congruent.
Step-by-step explanation:
In ∆ABC and ∆DCB
i) angleABC = angleDCB.....(each 90°)
ii) BC = BC .....( common side)
iii) AC = DB.....(given)
therefore by hypo-side test ∆ABC congruent ∆DCB
Δ = 1 + 4*20 = 81
x' = (-1 + 9)/2 = 4
x'' = (-1 - 9)/2 = -5
4² + 4 - 20 = 0
(-5)² - 5 - 20 = 0
Ok !