Trigonometry/Exercise: Congruent Triangles

Count The Triangles (With Labels)

• Label the vertices as shown in the diagram on the right.
• Now list the triangles using the letters at the corners, for example $\mathrm{△}ADE$ is a triangle. The symbol '$\mathrm{△}$' before the $ADE$ is just read as 'triangle'. You should put the symbol before the triangles you list, so your list might start:

$\mathrm{△}ACE,\mathrm{△}ADE,$

• Now, which of the triangles you have listed are congruent to each other?
• Which of the triangles you have listed are similar to each other but are not congruent?
• Do any of the triangles have an obtuse angle (an angle greater than 90 degrees)?