Vertical Angles
Vertical Angles are the angles opposite each other when two lines cross
They are called "Vertical" because they share the same Vertex (or corner point)
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In this example, a° and b° are vertical angles. The interesting thing here is that vertical angles are equal: a° = b°(in fact they are congruent angles) |
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Example: Find angles a°, b° and c° below:
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Because b° is vertically opposite 40°, it must also be 40° A full circle is 360°, so that leaves 360° - 2×40° = 280° Angles a° and c° are also vertical angles (and must be equal), which means they are 140° each. Answer: a = 140°, b = 40° and c = 140°. |
Note: They are also called Vertically Opposite Angles, which is just a more exact way of saying the same thing.