Formula for area of triangle: A= 1/2 bh Where b is the base and h is the height of the triangle. Here, h= b-9 A=56 m^2 Put values in formula. 56= 1/2 (b) (b-9) 56=b(b-9)/2 Multiply both sides by 2. 112=b^2-9b or b^2-9b-112=0 Factorise the equation. b^2-16b+7b-112=0 b(b-16)+7(b-16)=0 (b+7)(b-16)=0 Using zero factor theorem. b+7=0 or b=-7 and b-16=0 or b=16 Ignore the value b=-7, because length cannot be negative. So length of base=16 m
