Khan Academy
Khan Academy: Intro to Inverse Trig Functions
Learn about arcsine, arccosine, and arctangent, and how they can be used to solve for a missing angle in right triangles.
Curated OER
Webmath: Find Out Things About a Right Triangle
Gives basic info about a right triangle. Also students can substitute values for sides or angles in order to find missing values. The method for solving is then explained.
ClassFlow
Class Flow: The Law of Cosines
[Free Registration/Login Required] This flipchart defines and uses the law of cosines to find the missing sides and angles of oblique triangles.
CK-12 Foundation
Ck 12: Geometry: Laws of Sines and Cosines
[Free Registration/Login may be required to access all resource tools.] This concept teaches students to find missing sides and angles in non-right triangles using the Laws of Sines and Cosines.