#### notes

Area of triangle ECD = `1/2` h × c = `1/2` x 12 x10 = 60 sq m.

Area of rectangle ABCE = h × a = 12 × 20 = 240 sq m

Area of trapezium ABDE = area of triangle ECD + Area of rectangle ABCE = 60 + 240 = 300 sq m

We can write the area by combining the two areas and write the A(trapezium)

area of ABDE = `1/2` h x c+ h x a

`= h(c/2+a)`

`=h(c+(2a)/2)`

`=h(c+a+a/2)`

`=(h(b+a))/2`

`= ("height" ("sum of parallel sides"))/2`

by substituting the values of h,b and a in this expression, we find `(h(b+a))/2` =300 sq.m