Find the equation of the tangent to the circle \(x^2 + y^2 = 25 \) at the point (3, -4). The tangent will have an equation in the form \(y = mx + c\) so to find the equation you need to find the ...

One method of obtaining this equation is to integrate dxdy over the area of a circle. Well ... in the past to find the area under a curve on a graph (before technology gave us better methods).

The top part of that image is the equation itself. The bottom part is a graph of the equation, which, as you can see, is exactly the same. To be fair, this equation cheats a little bit.

Save guides, add subjects and pick up where you left off with your BBC account. Find the equation of a circle with radius 3 units and centre (0, 0). The radius, \(r = 3\) and \(r^2 = 9\), so the ...