EasyMathematicsHigh School (9–10)Mensuration › Areas and PerimetersNumericalBoard Exam

A coin has a radius of 1.75 cm. Find its circumference and the area of one face. Take π = 22/7.

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

A coin has a radius of $1.75\ \text{cm}$ . Find its circumference and the area of one face. Take $\pi = \dfrac{22}{7}$ .

Need a reminder? The key ideaShow

The circumference is $C = 2\pi r = \pi d$ and the area is $A = \pi r^2$ . Use $\pi = \dfrac{22}{7}$ only when the question says so. Change all lengths to one unit first, and remember $1\ \text{m}^2 = 10\,000\ \text{cm}^2$ .

The worked solution

Have you tried it?

Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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