Maths Olympiad Prep

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, 2025

Geometry Difficulty 2.6 Junior Find the answer Canada

Four of the angle measurements $62°,85°,99°,108°,114°$\$62\degree, 85\degree, 99\degree, 108\degree, 114\degree\$ are the measures of the angles in the same
quadrilateral. Which angle measure is not?

Pick one

Solution

The sum of the four angle measurements in a quadrilateral is
360°360\degree.

The sum of the five angle measurements given is 62°+85°+99°+108°+114°=468°62\degree+85\degree+99\degree+108\degree+114\degree=468\degree.

The difference, 468°360°=108°468\degree-360\degree=108\degree, is the
measure of the angle that is not in the quadrilateral.

(We may confirm that 62°+85°+99°+114°=360°62\degree+85\degree+99\degree+114\degree=360\degree.)

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.