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Answer:
a) 14.4 cm
b) 45.2 cm to 1 d.p
Step-by-step explanation:
If the radius of the circle below is 7.2 cm, then
a) the diameter of the circle = 2 × its radius
= 2 × 7.2
= 14.4 cm
b) The circumference of the circle = 2πr
= 2 × 3.14 × 7.2
= 6.28 × 7.2
= 45.216
= 45.2 cm to 1 d.p
Answer:
a) 14.4 cm
b) 45.2 cm
Step-by-step explanation:
The diameter of a circle is the longest straight line segment that passes through the center of the circle, connecting two points on its circumference. It is twice the length of the radius. Therefore, the formula for the diameter (d) of a circle in terms of its radius (r) is:
[tex]\sf d=2r[/tex]
Given that the radius of the circle is 7.2 cm, substitute d = 7.2 into the diameter formula:
[tex]\sf d=2 \times 7.2 \\\\ d = 14.4\; cm[/tex]
So, the diameter of the circle is:
[tex]\LARGE\boxed{\sf 14.4\; cm}[/tex]
[tex]\dotfill[/tex]
The formula for the circumference of a circle is:
[tex]\sf C=\pi d[/tex]
where d is the diameter of the circle.
From part (a), we determined that the diameter of the circle is 14.4 cm. Therefore, to find the circumference, substitute d = 14.4 into the circumference formula:
[tex]\sf C=\pi \times 14.4 \\\\C=45.23893421169... \\\\C=45.2\; cm\;(1\;d.p.)[/tex]
So, the circumference of the circle rounded to one decimal place is:
[tex]\LARGE\boxed{\sf 45.2\; cm}[/tex]