To find the equation of a circle when you know the radius and centre, use the formula \({(x - a)^2} + {(y - b)^2} = {r^2}\), where \((a,b)\) represents the centre of the circle, and \(r\) is the ...

Want to calculate the radius of a circle from its area or perimeter? Here are the key formulas that no one explains clearly! ...

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 ...

Monash University researchers have extended Descartes’ Circle Theorem by finding a general equation for any number of tangent ...