Math PicnicEvery sheet is a promise

Vertical angles, step by step

When two straight lines cross, the angles opposite each other are equal.

Practice Practice sheetNew questions
The question
57°x degrees

Vertical angles

57°andx
opposite=equal
57°→57°
  1. Two straight lines crossing. This is the pair that is NOT a subtraction — nothing adds to 90 or 180 here, so reaching for either is the mistake.
  2. Angles opposite each other at a crossing are EQUAL. Each one is what is left when the same straight line is taken away from the same straight line, so they cannot differ.
  3. So x is 57° — the same as the one across from it, not 180 minus it.

How it works.

  1. 01

    Two straight lines crossing. This is the pair that is NOT a subtraction — nothing adds to 90 or 180 here, so reaching for either is the mistake.

  2. 02

    Angles opposite each other at a crossing are EQUAL. Each one is what is left when the same straight line is taken away from the same straight line, so they cannot differ.

  3. 03

    So x is 57° — the same as the one across from it, not 180 minus it.

Pick another skill