Answer:
a = 12 yd
Step-by-step explanation:
From the pythagoras theorem
(hypotenuse)^2 = side^2 + side^2
20^2 = 16^2 + a^2
400 = 256 ^ a^2 subtract 256 from both sides
144 = a^2 the square root of 144 is 12
12 = a
