Drawing a diagonal splits the trapezium into two triangles having bases a and b, each sharing perpendicular height h. Summing their areas gives (1/2)ah + (1/2)bh = (1/2)(a + b)h.
By dividing a trapezium into two triangles show that its area is, half the sum of the parallel sides multiplied by the height (the same formula as the one given above).
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Let the parallel sides of the trapezium have lengths a and b and let the perpendicular distance between them be h.
Drawing a diagonal connects opposite vertices and divides the trapezium into two non-overlapping triangles:
Total area of trapezium = Area of first triangle + Area of second triangle
= (1/2)ah + (1/2)bh = (1/2)(a + b)h.
Hence proved.
For more NCERT Solutions of Class 9 Ganita Manjari Chapter 6 Measuring Space: Perimeter and Area Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/maths/ganita-manjari-chapter-6/