Radius from Area | In under 2 minutes #gcse #maths

Added: 2026-05-25

[00:00:00]Okay, so if you give me 2 minutes, I will teach you how to get the radius from knowing the area of the circle. So, let's say that the area here is let's say 100 cm squared.

[00:00:16]So, and I want to find the radius. So, the rule for the area is pi r squared.

[00:00:24]So, how do I get r from knowing that? Let's put the values in the equation. The area is 100.

[00:00:31]Pi is a fixed number and we know how to get it from the calculator. If you don't, watch our previous video.

[00:00:38]And r squared is the unknown. So, I will divide by pi both sides. So, I divide by pi, divide by pi.

[00:00:50]So, 100 / pi = r squared.

[00:00:55]If I put that in the calculator, so 100 / shift 7, which is pi, I'll get 31.83.

[00:01:05]And if I square root that, so r is 5.6 4.

[00:01:15]So, all you need to do is get the square root of that result and you will get this in cm.

[00:01:21]Okay, now hopefully you got that. I will give you an example to try and I also want to see radius, but the area in this case is going to be 150 cm squared.

[00:01:36]Have a go at that and let me know what you get in the comment or watch the next video for the full solution. Thank you for watching.