Answer:
21
Step-by-step explanation:
You can solve this by using 2 right angle triangles.
10 and 17 are both hypotenuses. The 8 is common to both
10 and 8
Length1 = sqrt(10^2 - 8^2) = sqrt(100 - 64) = sqrt(36) = 6
17 and 8
Length2 = sqrt(17^2 - 8^2) = sqrt(289 - 64) = sqrt(225) = 15
The third side
Length3 = Length1 + Length2
Length3 = 15 + 6
Length3 = 21
