Lets say the base is x and the height is y. The new base would be 1.2x and the new height would be 1.3y
Area of a triangle is base times height divided by 2:
1.2x*1.3y/2 = (1.2*1.3 + x*y)/2 = 1.56xy/2 = 0.78xy = 78% of xy
But a normal area would be 50% of xy
78% - 50% = 38%
ANSWER: 38% increase
