Lesson

Being able to identify an angle can help us in this lesson. Let's try this problem to review.

Which of the following is a right angle?

A

B

Worked Solution

Idea summary

A right angle is exactly 90\degree.

This video explains about acute, right, obtuse, straight, and reflex angles, as well as revolutions.

Select the obtuse angle:

A

B

C

D

Worked Solution

Idea summary

A full revolution is made up of 360 degrees, a single degree is written 1\degree.

Angle type | Angle size |
---|---|

\text{Acute angle} | \text{Larger than } 0 \degree, \text{smaller than } 90\degree. |

\text{Right angle} | 90\degree |

\text{Obtuse angle} | \text{Larger than } 90\degree, \text{smaller than } 180\degree. |

\text{Straight angle} | 180\degree |

\text{Reflex angle} | \text{Larger than } 180\degree, \text{smaller than } 360\degree. |

\text{Full revolution} | 360\degree |