3 is incorrect, should be 28.9
16^2 + 18^2 = EG^2
256 + 324
580 = EG^2
EG ≈ 24.08
16^2 + 24.08^2 = AG^2
256 + 580 = AG^2
836 = AG^2
AG ≈ 28.9
5 is incorrect:
The base is 8.
Draw an altitude the base.
Since the triangle is isoceles, it divides the base in half.
Half of that base is 4.
Two right triangles have been formed with one leg 4 and hypotenuse 8.
4^2 + b^2 = 8^2
16 + b^2 = 64
b^2 = 48
b ≈ 6.93
The height of the triangle is 6.93, the base is 8.
A = bh/2 = 8*6.93/2 ≈ 27.7 ≈ 28