Maths Olympiad Prep

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, 2026

Geometry Difficulty 1.2 Junior Find the answer Canada

Quadrilateral RSTURSTU is formed
by placing two equilateral triangles together, as shown.

The measure of ∠RST\angle RST is

Pick one

Solution

The measure of each of the three angles in an equilateral
triangle is 180°3=60°\dfrac{180\degree}{3}=60\degree.

Thus, $∠RSU=∠TSU=60°$.\$\angle RSU=\angle TSU=60\degree\$.

Since $∠RST=∠RSU+∠\$\angle RST=\angle RSU+\angle
TSU,thenthemeasureof, then the measure of ∠RST=60°+60°=120°$.\angle RST=60\degree+60\degree=120\degree\$.

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