# Math Help - Radian measure & its application

1. ## Radian measure & its application

A sector of a circle of radius r cm contains an angle of 1.2 radians. Given that the sector has the same perimeter as a square of area 36 cm^2, find the value of r.

2. Originally Posted by geton

A sector of a circle of radius r cm contains an angle of 1.2 radians. Given that the sector has the same perimeter as a square of area 36 cm^2, find the value of r.
You're kidding, right? Urgent homework on Christmas day. What is it - a last minute present for someone?

You should get that the perimeter of the square is 24 cm.
You should have a formula for arclength. Use it. The perimeter of the sector will be arclength + 2r = (.....) r.

Then 24 = (.....) r => r = ........

3. Originally Posted by mr fantastic
You're kidding, right? Urgent homework on Christmas day. What is it - a last minute present for someone?

You should get that the perimeter of the square is 24 cm.
You should have a formula for arclength. Use it. The perimeter of the sector will be arclength + 2r = (.....) r.

Then 24 = (.....) r => r = ........
Oh.. I’ve full respect about the Christmas day, but I’m from different country & religion.
Happy Christmas to all of you. And thank you to help me even in this holyday.

But I’ve to understand how you got perimeter of the square is 24 cm? Please tell me.

4. Originally Posted by geton
Oh.. I’ve full respect about the Christmas day, but I’m from different country & religion.
Happy Christmas to all of you. And thank you to help me even in this holyday.

But I’ve to understand how you got perimeter of the square is 24 cm? Please tell me.
the area of a rectangle is length times width. so the area of a square is the length of a side squared (since the length and width are equal). thus, the side length of the of a square with area 36 cm^2 is $\sqrt{36} = 6$. so the perimeter is 4 times this length, since the perimeter is the sum of the length of all the sides. thus we get 24

5. Thank you so much.

6. Originally Posted by geton
And thank you to help me even in this holyday.
holyday! Isn't that a good candidate for a cryptic crossword clue?
Thanks geton