Article reports on the discovery of a supermassive object 90 million light-years from Earth that may be an orphan black hole.

[Free Registration/Login Required] Students are given triangles and angles and are to determine which triangles are congruent. Click learn more to watch a video and challenge me to try a practice question.

Read an article from the Arkansas Archaeology Survey that traces a probable route of Hernando de Soto in what is now Arkansas. Evidence has been found especially in the Parkin site in northeast Arkansas.

Portraits of thirty-one Worcester residents. Among the names is Isaiah Thomas.

Find guidelines to help you "solve" triangles, which means finding the value of missing sides and angles. Provided are examples of six scenarios in which you can solve a triangle's missing measurements, as well as relevant equations,...

In this instructional activity on congruent triangles, students explore how to use postulates to identify if triangles are congruent by SSS, SAS, ASA, and AAS.

This activity works with a PowerPoint presentation to have students answer questions as to what method a pair of triangles can be proven congruent: SSS, SAS, ASA, AAS, HL.

Use the angle bisector theorem to find missing side lengths in triangles.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students the relationship between opposite angles and sides in triangles and how to use this relationship to compare triangles. students examine...

[Free Registration/Login may be required to access all resource tools.] Finding unknown sides in a triangle using other sides and angles.

[Free Registration/Login may be required to access all resource tools.] Find the unknown side of a triangle when two angles and a side are known.

Use the triangle congruence criteria SSS, SAS, ASA, and AAS to determine that two triangles are congruent. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

[Free Registration/Login may be required to access all resource tools.] In this lesson students compare sides and angles in triangles. Students examine guided notes, review guided practice, watch instructional videos and attempt practice...

The geometry tutorial investigates similar triangles. Students learn about the definitions and theorems of similar triangles. Topics included are angle-angle, side-side-side, and side-angle-side similarity. The activity has several...

Use the Angle Bisector Theorem to find missing side lengths in triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

[Free Registration/Login Required] This lesson helps teach congrence in triangles. Includes practice with postulates, theorems, and logical reasoning.

This interactive tool has student explore the topic of exterior angles of a polygon. The tool allows learners to change the number of sides to find the sum of the exterior angles of a variety of polygons.

In this activity, students will explore the concepts underlying the Triangle Inequality Theorem by comparing side lengths and angle measures of a triangle. They will use an interactive construction to see why this theorem is true.

In this activity, students investigate properties of triangles by randomly generating possible side lengths for triangles. They learn to determine if three line segments can form a triangle. They also learn to classify triangles as...

The geometry tutorial investigates congruent triangles. Students learn about the definitions and theorems on congruent triangles. Some topics included are angle-side-angle, side-side-side, and side-angle-side congruence postulates. The...

This site gives a very thorough explanation of how to tell if two triangles are congruent. Dr. Math explains why SSS, SAS, ASA determine that two triangles are congruent. The Dr. gives a few exercises for the reader to try then gives the...

Here is a site that clearly and thoroughly explains how to solve right triangles for any missing side or angle given any two pieces other sides or angles. There are example problems solved, problems for the student to attempt, and...

This lesson will define the phrase corresponding parts (e.g. angles, sides, etc.). It is 5 of 5 in the series titled "Corresponding Parts."

[Free Registration/Login may be required to access all resource tools.] This lesson introduces the Law of Sines for two cases.