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Equation of a Circle: Geometry Math Test – PDF Download

    Equation of a Circle – Geometry math test

    This 45-minute test has 9 questions worth 20 points. It covers the equation of a circle, finding the center and radius, completing the square, and locating points relative to a circle. Calculators are allowed. Show all work and leave radicals exact.

    Test information
    • Grade: Geometry
    • Chapter: Equation of a Circle
    • Common Core: G-GPE.A.1
    • Time: 45 minutes
    • Total: 20 points (Question 1: 2 pts; Question 2: 2 pts; Question 3: 2 pts; Question 4: 3 pts; Question 5: 3 pts; Question 6: 2 pts; Question 7: 2 pts; Question 8: 2 pts; Question 9: 2 pts)

    Question 1: Write the equation (2 points)

    Write the equation of the circle with center \((-4,3)\) and radius 6.

    Question 2: Equation from a graph (2 points)

    xy−3−2−11234567−6−5−4−3−2−11234C(2, −1)(5, −1)
    A circle on a coordinate grid.

    Write the equation of the circle shown. The center is at a lattice point, and the circle passes through (5, −1).

    Question 3: Center and radius (2 points)

    Find the center and the exact radius of the circle \((x+3)^{2}+(y-7)^{2}=50\).

    Question 4: Points and a circle (3 points)

    xy−5−3−11357−4−22468ABC
    Circle with points A, B and C.

    The circle \((x-1)^{2}+(y-2)^{2}=25\) is shown. Decide whether each point is inside, on, or outside the circle. Show the calculation. A\((4,6)\), B\((-2,3)\), C\((6,5)\).

    Question 5: Complete the square (3 points)

    The equation of a circle is \(x^{2}+y^{2}-4x+10y+13=0\). Rewrite it in standard form, and state the center and the radius.

    Question 6: Diameter endpoints (2 points)

    A circle has a diameter with endpoints \((-3,-2)\) and \((5,4)\). Write the equation of the circle.

    Question 7: Tangent circle (2 points)

    A circle has center \((6,-4)\) and is tangent to the x-axis. Write its equation.

    Question 8: Derive the equation (2 points)

    xyC(h, k)P(x, y)|x − h||y − k|r
    A point P(x, y) on a circle with center C(h, k).

    The circle shown has center \((h,k)\) and radius \(r\). Use the right triangle to show that every point \((x,y)\) on the circle satisfies the circle equation.

    Question 9: Points on a circle (2 points)

    The point \((5,y)\) lies on the circle \(x^{2}+y^{2}=169\). Find all possible values of \(y\).

    Equation of a Circle: Geometry test answer key

    See every chapter on the Geometry math page.

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