A pentagon is divided into three triangles by drawing diagonals from one of its vertices. The areas of two of these triangles are 24 cm2 and 30 cm2. The third triangle has a base of 12 cm and a height of 38 cm. What is the area (in cm2) of the pentagon?
282
Area of the third triangle: \(\tfrac12\times12\times38 = 228\) cm2.
Total area of the pentagon: \(24+30+228 = 282\) cm2.
Hence, the area of the pentagon is 282 cm2.
The shorter side of a rectangle is 15 cm less than the longer side. The numerical value of its area is equal to 5 times the numerical value of its perimeter. What is the length (in cm) of its longer side?