Similar Triangles

Today in MFM2P we started learning about triangles. We reviewed how to use protractors and rulers, and the students were tasked with creating a right angle triangle that had a 30 degree angle in it.

we needed quite a refresher about how to use a protractor to design our triangle, and how to measure angles.

The next challenge was to use a ruler and carefully measure the length of each side to the nearest tenth of a centimeter.

We talked about triangle vocabulary. We know that angles can be acute obtuse or right, and that these triangles that we made were all scalene. They are also all similar since they have the same angles. Since they have the same angles their sides will be proportionate.

We checked that theory by calculating the ratio of sides. We noticed that the small side divided by the long side was always about 0.5, the middle side divided by the long side was about 0.87 and the small side divided by the middle side was about 0.57. It didn’t matter what size our triangles were, the sides were all scaled up (or down) proportionally.

We’ll keep working on ratios and proportions and use that to solve problems moving forward in triangles and other contexts.