HKMO1213GCQ3

The figure below shows two straight lines AB and AC intersecting at the point A. Construct a circle with radius equal to the length of the line segment MN so that AB and AC are tangents to the circle. 下圖所示為兩相交於 A 點的直線 AB 及 AC 。 試構作一半徑等於線段 MN 的圓使得 AB 及 AC 均為該圓的切線。