Explaining, convincing and proving
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problemLens Angle
Find the missing angle between the two secants to the circle when the two angles at the centre subtended by the arcs created by the intersections of the secants and the circle are 50 and 120 degrees.
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problemSimilarly So
ABCD is a square. P is the midpoint of AB and is joined to C. A line from D perpendicular to PC meets the line at the point Q. Prove AQ = AD.
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problemComposite Notions
A composite number is one that is neither prime nor 1. Show that 10201 is composite in any base.
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problemTriangles Within Pentagons
Show that all pentagonal numbers are one third of a triangular number.
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problemThe Great Weights Puzzle
You have twelve weights, one of which is different from the rest. Using just 3 weighings, can you identify which weight is the odd one out, and whether it is heavier or lighter than the rest?
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problemSquare LCM
Using the hcf and lcf of the numerators, can you deduce which of these fractions are square numbers?
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problemGeometric Parabola
Explore what happens when you draw graphs of quadratic equations with coefficients based on a geometric sequence.
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problemDigital Counter
When the numbers from 1 to 1000 are written on a blackboard, which digit appears the most number of times?