In a 30-60-90 triangle, what is the hypotenuse if the short leg is 5?
A 30-60-90 triangle has fixed ratios between its sides. Know one side and the other two follow without any trigonometry.
Try this lessonFind the step that makes it click.
Pick a topic in math, science, chemistry, or writing. Try an example, get a clue, and practise at your pace.
No account or card needed. Practice answers stay on this page and aren’t saved.
1 lesson for “Special right triangles”
Also close
What is sin A when the opposite side is 3 and the hypotenuse is 5?
Trigonometry begins with one idea: a ratio of two sides. Label the sides for your chosen angle, and the ratio is mechanical.
Try this lessonWhy can't I just add the two legs?
Frida found the hypotenuse of a right triangle with legs 6 and 8 by adding 6 + 8 = 14. The lengths must be squared first.
Try this lessonWhere did the 180 degrees go?
Hana found the third angle of a triangle with angles 65 and 42 by writing 107. She added the two she had and never finished the problem.
Try this lessonWhat is sin of a 30-degree angle on the unit circle?
On the unit circle, every point's coordinates are (cos, sin). Learn a few landmarks and the special angles are solved.
Try this lessonWhy can't I just go left to right?
Jordan computed 3 + 4 * 5 by moving left to right: 3 + 4 = 7, then 7 * 5 = 35. The convention says multiply first.
Try this lessonWhy is x^2 - 36 not (x - 6)(x - 6)?
x^2 - 36 looks like an ordinary binomial, but it carries a special pattern. A difference of two squares always factors into a sum times a difference.
Try this lessonTry a step. See what clicks.
Work through an example, ask for a clue when you need one, then try a new question on your own.
Browse by subject
All of math, science, chemistry and writing lessons or search across the whole library above.
Learn by trying
Fill in one step at a time and check your answer. Need help? Tap “Give me a clue.”
Treat these examples as a starting point for a conversation, not as a replacement for your teacher’s guidance.
Need help with your own question? See how the family service works