Students will define an angle, identify its vertex and arms, and correctly name it using three letters.
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Defines angle, vertex, and arms.
Look around you. A pair of scissors, a compass, or even an open book all have something in common—they form angles. But what exactly is an angle in geometry?
Step-by-step example on how to name an angle using three letters.
Consider an angle formed by two rays, and , starting from a common point . How do we correctly write the name of this angle?
An angle is formed by two rays with a common vertex.
Every time you open a pair of scissors or a compass, you are looking at a real-world angle!
Faded example naming angles from a figure.
Look at the figure provided with points P, R, T, and Q. In this figure, the point T acts as the common starting point for multiple rays. This common starting point is called the vertex of the angles. To correctly name an angle, we use three letters where the vertex is always placed in the middle.
For the first marked angle formed by the arms TR and TQ, we place T in the middle to name it . Similarly, for the second marked angle formed by the arms TR and TP, we use the points on the arms and the vertex to name it .
MCQ testing angle naming order.
An engineer designs a corner joint where two metal beams meet at vertex A. The beams extend outward, passing through points B and C. Which of the following is an INCORRECT way to name this angle?
Name all angles formed by three intersecting lines.
By drawing lines between three non-collinear points A, B, and C, you create a triangle with three internal angles.
Your Task: Provide the correct 3-letter names for all three angles.
List the three angles using the 3-letter naming convention.
Explain how you determined the middle letter for each angle.