Answer:
240
Explanation:
it is 4 times the area of these right-angled triangles.
we calculate the area of one, and then multiply by 4 as they are all the same.
the missing side is (using Pythagoras)
17² = 8² + side²
289 = 64 + side²
side² = 225
side = 15
area of one triangle
T = 8×15/2 = 4×15 = 60
the rhombus area is
R = 4×T = 4×60 = 240