First of all we will have to find the area of ΔBDF Here, a = 17, b = 25, c = 12 ∴ s =
a+b+c
2
=
17+25+12
2
=
54
2
= 27 m
∴ Area of ΔBDF = √27(27−17)(27−25)(27−12) = √27×10×2×15 = √3×3×3×2×5×2×5×3 = 3 × 3 × 5 × 2 = 90 sq. m. Since Area of ΔBDF =
1
2
× base × height ⇒ 90 =
1
2
× 25 × height ∴ Height of the triangle, i.e., distance between the parallel sides of the trapezium =