LoC Activity: Obtuse Triangle
Move the slider so the triangle is obtuse.
Click the first check box.
1. Find AD and BD and use these to find the areas of the shaded rectangles.
Unclick the first check box. Click the second check box.
2. Find cos(180-C) and use it to find CE. Then find cosB (hint: to find cosB, make use of CE).
Click the third check box; unclick the others.
3. Find cos(180-C) and use it to find CF. Then find cosA (hint: to find cosA, make use of CF).
4. Use your work in (1) to compute c2 two ways. Then substitute your answers in (2) and (3) to rewrite your answer. What do you get for c2?