Rosyth Sch 2007 PSLE Math Prelim Q43

The area of the figure ABCD is 48.5 square cm . Find the length of BE.
(Give your answer to the nearest tenth)


Solution

Area of ACD
1/2 x 18 cm x 10.4 cm = 93.6 square cm

Area of ABC
93.6 square cm - 48.5 square cm = 45.1 square cm

Area of Triangle ABC ----- 1/2 x base x height
45.1 square cm = 1/2 x 18 cm x height

height = (45.1 sq cm x 2 ) divided by18 cm
= 5.01 cm ~ 5.0 cm (to the nearest tenth)

Answer: 5.0 cm