The parallel sides of trapezium are 65 cm and 49 cm and each of the non parallel sides is 10 cm. Find the area of Trapezium.
Draw CF || AD, intersecting AB in F and CE ⊥ BF.
CF || AD and AF || CD.
∴ AFCD is a parallelogram.
AF = CD = 49 cm (Opposite sides of parallelogram are equal)
AD = CF = 10 cm (Opposite sides of parallelograms are equal)
BF = AB – AF = 65 cm – 49 cm = 16 cm
ΔBCF is an isosceles triangle.
∴EF = EB= 16/2 = 8 cm (In an isosceles triangle, altitude from the vertex bisects the base)
In ΔCFE,
CE2 + FE2 = CF2
∴ CE2 = CF2 – FE2 = (10 cm)2 – (8 cm)2 = 100 cm2 – 64 cm2 = 36 cm2
⇒ CE = 6 cm
Area of trapezium
= ½ × (AB + CD) × CE
= ½ × (65 + 49) × 6
= ½ × 114 × 6
= 114 × 3
= 342 cm2