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The Hypotenuse

Part of the Right-Triangle Trigonometry section of Coddy's Trigonometry journey. Lesson 2 of 50.

A right triangle has one 90° corner, marked with a small square. The side across from that corner, the one that does not touch the square, is the hypotenuse. It is always the longest of the three sides.

$Right triangle ABC with the right angle at C and the hypotenuse AB$

Here the square is at C, so the hypotenuse is AB. Turn or flip the triangle and the rule still works: find the square first, then take the side that stays away from it. Never pick it by how long it looks, because figures are often drawn off scale.

Challenge

Triangle PQR has a right angle at P. Tap its hypotenuse. Then press Check.

Try it yourself

$Find the right part on the figure$

Find the right part on the figure

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Right-Triangle Trigonometry

1Sides of a Right Triangle

How Tall Is the Tree?The HypotenuseThe Opposite Side The Adjacent Side When the Angle Moves Recap: Naming the Sides

4Finding the Hypotenuse

The Unknown Below the Bar How Long Is the Kite String?A Leg Below the Bar Is the Answer Sensible?Recap: The Hypotenuse

7Elevation and Depression

Angle of Elevation Measuring From Eye Level Angle of Depression The Sun's Angle Two Triangles, One Height Recap: Looking Up and Down

2The Three Ratios

The Sine Ratio The Cosine Ratio The Tangent Ratio Choosing the Ratio Recap: The Three Ratios

5Finding an Angle

Inverse Sine Inverse Cosine Inverse Tangent The Angle of a Ramp Both Acute Angles Recap: Finding an Angle

8Reciprocal Ratios

Cosecant, Secant, Cotangent Exact Reciprocal Values A Side From a Cosecant A Ladder and a Secant Recap: Reciprocal Ratios

3Finding a Side

Sides at Any Angle Rounding the Answer Tangent: Leg From Leg A Ladder Against a Wall The Other Acute Angle Recap: Finding a Side

6Special Triangles, Exactly

The Two Special Triangles An Exact Hypotenuse The Side Next to 30°An Exact Angle Recap: Exact Values

9Final Challenges

Is the Ladder Safe?The Wheelchair Ramp Two Observers The Landing Plane The Kite The Sun's Angle, Exactly