You may be asked to show that two circles are touching, and say whether they're touching internally or externally. To do this, you need to work out the radius and the centre of each circle.

times {m_{tgt}} = - 1\) to find the gradient of the tangent. Find the equation of the tangent to the circle \({x^2} + {y^2} - 2x - 2y - 23 = 0\) at the point \(P(5, - 2)\) which lies on the circle.

If their circles are nested or nearly overlap so that the external angle of intersection is greater than 90 degrees, then you cannot claim that the means of the two groups are different. If, however, ...