Learning Resources

Focus J: Equations in Transformational Form

Test yourself (solution)

The equation of the original circle is , therefore its centre is at (-1 , 3) and its radius is 5.

If (-1 , 3) is translated 4 units right it goes to (3 , 3). If it is then translated 2 units down, it goes to (3 , 1). This is the centre of the new circle.

The radius is changed by a factor of 3, it thus becomes 3 x 5 or 15.

The new equation is thus: