CK-12 Geometry-Concepts

8.5. 30-60-90 Right Triangles http://www.ck12.org

8.5 30-60-90 Right Triangles

Here you’ll learn that the sides of a 30-60-90 right triangle are in the ratiox:x

√

3 : 2x.

What if you were given a 30-60-90 right triangle and the length of one of its side? How could you figure out the
lengths of its other sides? After completing this Concept, you’ll be able to use the 30-60-90 Theorem to solve
problems like this one.

Watch This

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52519

CK-12 Foundation: Chapter8306090RightTrianglesA

Watch the first half of this video.

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1362

James Sousa: Trigonometric Function Values of Special Angles

Now watch the first half of this video.

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1363

James Sousa: Solving Special Right Triangles

Guidance

One of the special right triangles is called a 30-60-90 triangle, after its three angles. To construct a 30-60-90 triangle,
start with an equilateral triangle.