I am given that the radius of the semi-circle is r and the short side of the rectangle is r and the long side 3cm. Both shapes have the same perimetre. Work out the value of r.

Any help i will be vvv thankful!!

Cheers..

Posted Wed 24th April, 2013 @ 11:50 by

Cinnamontree97
The perimeter of the rectangle is 3+3+r+r or simplified is 6+2r

2 pi r is the formula for the circumference of a circle.

These two equations must equal the same thing, therefore 6+2r=2pi r so if you rearrange that you will find the value of r :)

Hope this helps!

Answered Wed 24th April, 2013 @ 18:48 by

Chantelle
Thanks for that CHANTELLE - really healpful!

Cheers..

CASS

Answered Wed 24th April, 2013 @ 21:35 by

Cinnamontree97