How it works
This free find the missing angle worksheet has 12 figures on one page: 3 each in a triangle, in a quadrilateral, on a straight line and around a point. Press Print or PDF, or New sheet for other figures. The key shows each subtraction.
Read the full guide
Triangles and quadrilaterals first
In a triangle gives two angles and asks for the third. In a quadrilateral gives three angles of four. Every polygon is drawn to its true angles, so an obtuse angle looks obtuse. Under On the sheet, leave only On a straight line lit for an angles on a line worksheet. Vertical angles is a fifth pill, off at first.
Two ways to make it harder
With Missing angles are on Numbers, set Unknowns in a figure to Up to 2 for isosceles triangles with tick marks and exterior angles, labeled a and b. Up to 3 adds parallelograms. Or pick One expression and an angle reads 2x + 10; the unknowns setting then changes nothing. A finding missing angles worksheet for grade 8 can use either.
- A small square means 90° and carries no number. Unticking Right-angle markers drops the squares, but 90° can still print as a number or answer.
- Figures with two answers print 2 to a row, so 12 problems at Up to 2 take 2 pages.
- The Score line counts answers, not figures: 12 problems at Up to 2 can read Score / 15.
Questions and answers
How do you find a missing angle?
Add the angles you know and subtract from the total: 180° on a straight line or in a triangle, 360° around a point or in a quadrilateral. On the opening sheet, a triangle with 39° and 52° gives x = 89°.
How do I make an angles around a point worksheet for grade 8?
Under On the sheet, leave only Around a point lit. With Numbers, 3 to 6 angles meet at each point and 12 figures fit one page. For grade 8, choose Expressions, so students write an equation that adds up to 360.
Does this missing angles worksheet come with answers?
Yes, on a page of its own. Each answer prints with its working, as in x = 70° (360 − 90 − 115 − 85). At the expression settings the key gives x and the labeled angle, as in x = 15 (2x + 10 = 40°).
Which grades is it for?
One expression has students write and solve an equation for an unknown angle, the single-step part of Common Core 7.G.5; the standard asks for multi-step problems. 8.G.5 includes the angle sum and exterior angle of triangles; Up to 2 adds exterior angles.