Question

If two parallel sides of a trapezium are 80 cm and 60 cm and other sides are 24 cm and 28 cm, two then the area of trapezium is (in sq. cm)​

Answer 1

Answer:

Step-by-step explanation:

Area of a trapezium = (h/2)(a + b) where h = height and a and are the lengths of parallel sides.

If we draw 2 perpendicular lines from 2 upper points on a parallel side to the other parallel side we get 2 triangles whose bases are x and 20-x.

By Pythagoras h^2 = 28^2 - x^2  and also h^2 = 24^2 - (20 - x)^2 so

28^2 - x^2 = 24^2 - (400 + x^2 - 40x)

28^2 - x^2 = 24^2 - 400 - x^2 + 40x

28^2 - 24^2 + 400 = 40x

x = 608/40

= 15.2 cm.

So h^2 = 28^2 - 15.2^2 = 552.96

h = 23.515

So the area of the trapezium = 23.515/2 * (80+60)

= 1646.06 to 2 dec places.

Answer 2

Answer:

Step-by-step explanation:

A = a + b/2*h = 80+60/2 =70h.

A = a + b/2*h = 42/2 =21h.

A = 70+21/2h = 45.5h.