Angles, Triangles and Trigonometry - June 2007, Stage 3&4

Problems

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Round and Round and Round

Stage: 3 Challenge Level: Challenge Level:1

Where will the point stop after it has turned through 30 000 degrees? I took out my calculator and typed 30 000 ÷ 360. How did this help?

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Can You Explain Why?

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

Can you explain why it is impossible to construct this triangle?

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Where Is the Dot?

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

A dot starts at the point (1,0) and turns anticlockwise. Can you estimate the height of the dot after it has turned through 45 degrees? Can you calculate its height?

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Sine and Cosine

Stage: 4 Challenge Level: Challenge Level:1

The sine of an angle is equal to the cosine of its complement. Can you explain why and does this rule extend beyond angles of 90 degrees?

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Eight Ratios

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Two perpendicular lines lie across each other and the end points are joined to form a quadrilateral. Eight ratios are defined, three are given but five need to be found.

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Two Regular Polygons

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Two polygons fit together so that the exterior angle at each end of their shared side is 81 degrees. If both shapes now have to be regular could the angle still be 81 degrees?

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Wedge on Wedge

Stage: 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Two right-angled triangles are connected together as part of a structure. An object is dropped from the top of the green triangle where does it pass the base of the blue triangle?