Write the area equation= 102 Simplify x*(x+5) = 2*102 = 204. Notice that 204 = 4*51 = 4*3*17 = 12*17 is the product of two numbers, 12 and 17, whose difference is 5. After noticing it, you just have the ANSWER. The base is 12 cm. The altitude is 17 cm.