Question

Find the perimeter of this semi-circle with diameter, d = 26cm.

Give your answer rounded to 1 DP.
d cm

Answer 1

66.8 cm

Explanation:

to find the curved perimeter bit of the semicircle, find the circumference.

so diameter×pi

26×pi = 26pi = 8.68140899

multiply that by what fraction of the full circumference the semicircle is.

because it is semi, it is half, so 1/2 × 26pi

this gives 13pi which you add to the diameter to find the flat part of the semicircle.

13pi +26= 66.8407045cm

Answer 2

81.64

Explanation:

r=d÷2

=26÷2

=13

p= 2*22/7*13

=81.64