Angles on a straight line

Task goals

• Find a missing angle on a straight line from a diagram, using the fact that two adjacent angles on a straight line sum to $180^\circ$.
• Find a missing angle given as a word description, such as one angle being a multiple of or a fixed amount bigger than the other.
• Solve for an unknown $x$ when the two adjacent angles on a straight line are given as algebraic expressions, including from a diagram.
• Solve angles-on-a-straight-line problems where the two angles are given as a ratio.
• Find a missing angle when three or four angles together lie along a straight line.
• Explain whether a given pair or set of angles could lie on a straight line, and identify the error when a student's claimed pair does not sum to $180^\circ$.
• Write and solve their own pair of adjacent angles on a straight line where one angle is algebraic and the other numeric.