Pythagoreom theorom, assuming that's a right triangle
sqrt(20^2+20^2 = 28.284
1. 28.284
2. 28.284
1/2bh
28.284*(1/2)*16 = 226.274
3. 226.274
226.274+(28.284^2) = 1026.259
4. 1026.259
All assuming that that is a right triangle
Don't answer it yet. Let me review my answer or another person gives input. Been almost 3 years since done this stuff.