Chapter 7 – Circles
Practice set 28
1. Draw circles with the radii given below.
(1) 2 cm
Ans:
(2) 4 cm
Ans:
(3) 3 cm
Ans:
2. Draw a circle of any radius. Show one diameter, one radius and one chord on that circle.
Ans:
Diameter – LM
Radius – OP
Chord – CD
Practice set 29
1. If the radius of a circle is 5 cm, what will its diameter be?
Ans:
Radius = 5 cm
Diameter = 2 × Radius
∴ Diameter = 2 × 5
∴ Diameter = 10 cm
Diameter will be 10 cm.
2. If the diameter of a circle is 6 cm, what will its radius be?
Ans:
Diameter = 6 cm
Radius = Diameter ÷ 2
∴ Radius = 6 ÷ 2
∴ Radius = 3 cm
Radius will be 3 cm.
3. Complete the following table by filling in the blanks.
Ans:
(1) Radius = 4 cm
Diameter = 2 × Radius
∴ Diameter = 2 × 4
∴ Diameter = 8 cm
Diameter will be 8 cm.
(2) Diameter = 16 cm
Radius = Diameter ÷ 2
∴ Radius = 16 ÷ 2
∴ Radius = 8 cm
Radius will be 8 cm.
(3) Radius = 9 cm
Diameter = 2 × Radius
∴ Diameter = 2 × 9
∴ Diameter = 18 cm
Diameter will be 18 cm.
(4) Diameter = 22 cm
Radius = Diameter ÷ 2
∴ Radius = 22 ÷ 2
∴ Radius = 11 cm
Radius will be 3 cm.
Practice set 30
In the table below, write the names of the points in the interior and exterior of the circle and those on the circle.
Ans:
Points in the interior of the circle = Point Y, Point R, Point T, Point X
Points in the exterior of the circle = Point M, Point W, Point Z
Points on the circle = Point P, Point N
Practice set 31
1. In the figure given alongside, points S, L, M and N are on the circle. Answer the questions with the help of the diagram.
(1) Write the names of the arcs with end-points S and M.
Ans: Arc SLM and Arc SNM
(2) Write the names of the arcs with the end-points L and N.
Ans: Arc ABC, Arc BCD, Arc CDA and Arc DAB.
3. Give the names of the arcs that are made by points P, Q, R, S and T in the figure.
Ans: Arc PQR, Arc QRS, Arc RST, Arc STP and Arc TPQ.
4. Measure and note down the circumference of different circular objects. (It is convenient to use a measuring tape for this purpose.)
Ans: Students should do this on their own.