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Last updated on September 24, 2025
In geometry, rotation is a transformation that turns a figure about a fixed point. A one-eighty-degree rotation means turning the figure upside down. In this topic, we will learn the formula for a 180-degree rotation.
Rotation involves turning a figure around a point. Let's learn the formula to calculate the coordinates of a figure after a 180-degree rotation.
A 180-degree rotation turns a point (x, y) to (-x, -y).
The formula for a 180-degree rotation about the origin is: If (x, y) is a point, then its image after a 180-degree rotation is (-x, -y).
A one-eighty-degree rotation is equivalent to two right-angle turns.
The figure is rotated halfway around a circle.
For example, a point (a, b) becomes (-a, -b) after a 180-degree rotation.
A 180-degree rotation has specific properties:
The shape and size of the figure remain unchanged.
The orientation of the figure is reversed.
It is a special case of rotational symmetry, where the figure looks the same after a half-turn.
In geometry and real life, understanding the 180-degree rotation formula helps analyze and manipulate figures.
It's essential for solving problems involving rotational symmetry.
It helps in understanding transformations in coordinate geometry.
It's useful in fields like computer graphics and engineering for object manipulation.
Students might find geometry transformations tricky. Here are some tips to master the 180-degree rotation formula:
Visualize the rotation on graph paper to see the effect.
Remember that a 180-degree turn inverts the signs of both coordinates.
Practice by applying the formula to different points and figures.
Students often make errors when applying the 180-degree rotation formula. Here are common mistakes and ways to avoid them.
What is the image of the point (3, 4) after a 180-degree rotation about the origin?
The image is (-3, -4).
Using the formula for 180-degree rotation, the point (3, 4) becomes (-3, -4).
Find the image of (-5, 7) after a 180-degree rotation.
The image is (5, -7).
Using the 180-degree rotation formula, the point (-5, 7) becomes (5, -7).
What happens to the point (0, -8) after a 180-degree rotation?
The image is (0, 8).
Applying the 180-degree rotation formula, the point (0, -8) becomes (0, 8).
Determine the image of the point (-9, -2) after a 180-degree rotation.
The image is (9, 2).
Using the formula, the point (-9, -2) becomes (9, 2) after a 180-degree rotation.
Find the image of (6, -1) after a 180-degree rotation.
The image is (-6, 1).
Applying the 180-degree rotation formula, (6, -1) becomes (-6, 1).
Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.
: He loves to play the quiz with kids through algebra to make kids love it.