Question

Find the surface area of the part of the plane 5x + 5y + z = 25 that lies above the triangle formed by the three points (4,2,0)(8,2,0)(8,6,0)

Answer 1

5x +5y +z= 25
5x+ 5y - 25 +z
5x + 5y -25 = -z
5*5=25
25*4=100
100-25=75
-z=75