Use a triangle area formula that works when the height is unknown. The eighth installment in a 16-part series on trigonometry revisits the trigonometric triangle area formula that previously was shown to work with the acute triangles....

Observe the change in the trigonometric ratios as angles vary. An interactive provides the values of trigonometric ratios for both acute angles in a right triangle. Pupils create a right triangle to match given criteria and find the...

Solving triangles is a breeze. Young boat enthusiasts solve problems involving triangles in the context of sails on a boat. They must apply different strategies, including the Law of Cosines and area formulas.

The topic of trigonometric ratios is often covered with loads of rote memorization baked into the activity. This activity set, however, leans more on using similar triangles and discovery learning to help young geometers develop a deeper...

Good fences make good gardens. Individuals use an interactive to see how angles and sides relate in a triangular-shaped garden fence. They apply the Law of Sines to find the length of the garden gate (third side of triangle) given two...

Learn how to solve a triangle. Young mathematicians view a video that explains how to apply trigonometry to find missing sides and angles of a right triangle. A worksheet tests their understanding of the concept.

It is all right to spend some time with a review. After watching a short review video covering the materials from the unit, pupils work through 23 review problems. Scholars work on problems involving the Pythagorean Theorem and its...

Prove the Law of Sines two ways. The ninth segment in a series of 16 introduces the Law of Sines to help the class find lengths of sides in oblique triangles. Pupils develop a proof of the Law of Sines by drawing an altitude and a second...

Determine the distance between two trees from afar. Pupils use an interactive resource to create two right triangles using trees and a plane. They determine the horizontal legs of each triangle to find the distance between the two trees.

Use the Law of Cosines and the Law of Sines to solve problems using the sums of vectors. Pupils work on several different types of real-world problems that can be modeled using triangles with three known measurements. In the process,...

Build upon the Pythagorean Theorem with the Law of Cosines. The 10th part of a 16-part series introduces the Law of Cosines. Class members use the the geometric representation of the Pythagorean Theorem to develop a proof of the Law of...

Is it a right triangle or not? Introduce scholars to the converse of the Pythagorean Theorem with a lesson that also provides a proof by contradiction of the converse. Pupils use the converse to determine whether triangles with given...