A spiral is made up of successive semicircles,with centers alternately at A and B,starting with centre at A,of radio 0.5 cm,1.0 cm,1.5 cm,2.0 cm,….as shown in fig.What is the total length of such a spiral made up of thirteen consecutive semicircles (Take `pi=22/7`)

A toy is in the form of a cone of radius 3.5 cm mounted on a hemisphere of same radius. The total height of the toy is 15.5 cm. Find total surface area of the toy (Use pi = 22/7 ).

In a cuboidal solid metallic block of dimension 15 cm xx 10 cm xx 5 cm , a cylindrical hole of diameter 7 cm is drilled out. Find the volume and surface area of the remaining block (pi=22/7) .

In Fig 13,ABCD is a square of side 5.6 cm.As shown in the figure,four circles are drawn with centres A,B,C and D respectively.Find the area of the shaded region in the diagram. (pi=22/7)

A conducting sphere of radius 10cm has unknown charge. If the electric field at 20cm from the centre of the sphere is 1.5 * 10^3NC^-1 and points radially inward, what is the net charge of the sphere?

A wooden article was made by scooping out a hemisphere from each end of a solid cylinder,as shown in Fig.13.11.If the height of the cylinder is 10 cm,and its base is of radius 3.5. find the total surface area of the article.

A bucket made up of metal sheet is in the form of a frustum of height 16 cm (closed at the lower end but open at the upper end) with radii of the lower and upper ends are 8 cm and 20 cm respectively. Find the cost of the bucket if the cost of the metal sheet used is ₹ 15.00 per 100 cm (pi = 3.14) .

The radius of a sphere is measured to be (2.1±0.5)cm . Calculate its surface area with error limit .