Turning About a Point
Part of the Transformations & Constructions section of Coddy's Geometry journey. Lesson 11 of 61.
A rotation turns a shape about a fixed point, the center. Every point keeps its distance from the center and turns through the same angle. By convention a positive angle turns counterclockwise.
Here PQR turns 90° clockwise about the origin O. P(3, 1) is 3 right and 1 up from O; after a quarter turn clockwise that step becomes 1 right and 3 down, so P' is (1, -3). The image keeps its size and shape and is not flipped: the corners still go round in the same order.
On the board, the move is Rotate: choose 90°, 180° or 270°, the direction and the center (the origin unless you change it), then press Apply.
Challenge
Turn triangle ABC about the origin onto the dashed target: choose the angle and the direction, press Apply, then press Check.
Try it yourself
Move the shape onto its target
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Transformations & Constructions
7Drawing on Squared Paper
Lengths by PythagorasPerpendicular StepsSquares by AreaRight Triangles by AreaMidpoints on the GridRecap: Squared Paper10Perpendiculars and Parallels
Perpendicular From a PointPerpendicular at a PointParallel Through a PointTools You Have EarnedRecap: Parallels5Dilations
Scaling From a CenterShrinking a ShapeDilating About a PointNegative Scale FactorsRecap: Dilations8Compass and Straightedge
Circles Keep DistancesWhy the Sides MatchAngles You BuiltA 60° AngleRecap: Equilateral Triangle3Rotations
Turning About a PointThe Half TurnQuarter-Turn RulesA Center Off the OriginRecap: Rotations