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Recap: Three Sides

Part of the Triangles Without Right Angles section of Coddy's Trigonometry journey. Lesson 17 of 37.

Challenge

A triangle has sides 9 cm, 12 cm and 16 cm. Find the angle θ across from the 12 cm side, to two decimal places, and press Check.

Try it yourself

$Use the figure to find theta$

Use the figure to find theta

All lessons in Triangles Without Right Angles

1Across the Lake

Across the Lake Why the Law of Sines Holds Two Coast Stations Recap: Law of Sines

4Law of Cosines: SSS

Three Sides, One Angle The Largest Angle A Triangular FieldRecap: Three Sides

7Bearings and Navigation

Reading Bearings Two Ships From Port Turning Off Course Finding a Course Angle Recap: Ships at Sea

2The Ambiguous Case

Finding an Angle Two Triangles Radio Coverage Recap: How Many Triangles?

5Which Law to Use

Sines or Cosines?Not Between Three Towns Recap: Pick the Law

8Final Challenges

Final: Across the Canyon Final: Every Triangle Final: A Plot of Land Final: Ship and Plane Final: The Largest Angle

3Law of Cosines: SAS

The Law of Cosines An Obtuse Angle Between Through the Hill A Hooked Drive Recap: Two Sides, One Angle

6Area of a Triangle

Area With a Sine Area With an Obtuse Angle Working Backwards The Angle From the Area Heron's Formula Recap: A Garden Bed