Answer:
Step-by-step explanation:
lets say "a" for the empty line,
for small triangle; y^2 = 2^2 + x^2
right triangle; we say a for empty line, a^2= 6^2 + x^2
and big triangle covering both triangles, 8^2 = y^2 + a^2
lets add left sides and right sides in each;
x^2 + 4 + x^2 + 36 + y^2 + a^2 = y^2 + a^2 + 64 and we can delete same things for both sides
y^2 and a^2 can be deleted and 4+36 - 64
2(x^2)=24
x^2= 12
and x will be √12
so, y^2 = x^2 + 2^2 which means y^2 = 12+4 y=16
Edited in the comment ............
