Answer:
The base is 9 cm . Because the formula of area a triangle is 1/2 or half base times height. So if the area is 36, you subtract 18, which is the height. leaving 18 ( 36 -18 = 18) Then you dived 18 by 2. Since to find half of a number you dived by 2. Which is 9 ( 8÷2=9 )