Menu

English

The Adjacent Side

Part of the Right-Triangle Trigonometry section of Coddy's Trigonometry journey. Lesson 4 of 50.

Two sides touch θ. One of them is the hypotenuse. The other is the adjacent side, which means lying next to: it runs from θ to the right angle.

$Right triangle PQR, right angle at P, θ at R, all three sides named$

So any right triangle is named in three looks. The side across from the square is the hypotenuse. Of the two sides left, the one away from θ is opposite, and the one touching θ is adjacent. Here θ is at R and the square at P, so PR is adjacent, PQ is opposite and QR is the hypotenuse.

Challenge

Triangle DEF has a right angle at D, and θ is at E. Tap the side adjacent to θ. 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 Hypotenuse The Opposite SideThe Adjacent SideWhen 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