A rhombus shaped sheet with perimeter 40 cm and one diagonal 12 cm, is painted on both sides at the rate of Rs 5 per . Find the cost of painting.
[Rs. 960]
Let ABCD be a rhombus thus AB = BC = CD = DA = x (Let)
Area of rhombus = 2 Ar(ABC) [diagonal of rhombus divides it into two triangles of equal area]
Now, we find area of triangle using Heron’s formula
Now, Area of rhombus = 2 Ar(ABC)
We find the cost of painting
Thus,
Hence, the cost of the painting both sides of the sheet = 2 480 = Rs. 960.