The lengths of the parallel sides of a trapezium are 51 cm and 21 cm, and that of each of the other two sides is 39 cm. what is the area ( in cm²) of the trapezium?

The ratio of the sides of a triangle is 3: 4: a and the area of this triangle is 216 square cm. And the perimeter of this triangle is 72 cm. Then the value of a will be -

What is total surface area of a cone where, r’ is radius and ‘l’ is slant height?   

If the perimeter of a circular plot is equal to the perimeter of a square plot, what will be the ratio of their areas?

The length, breadth and height of a room is 21 metres, 12 metres and 16 metres. What will be the length of the largest rod that can be placed in that room?

The length of a rectangle is 6 cm more than its width and its perimeter is 100 cm. If the area of this rectangle is closest to the area of a circle, then what is the circumference of that circle?

A rectangular grass plot 80 m × 60 m has two roads, each 10 m wide, running in the middle of it; one parallel to length and the other parallel to breadth. Find the cost of gravelling the roads at ₹ 2 per m². 

A polygon has 14 sides then find out No. of diagonals in that polygon.