Category
Trigonometry
Identities, transformations, and angles that refuse to simplify.
Trigonometry sits between algebra and geometry, and contest problems exploit both sides of it. Identities compress an ugly expression; the unit circle turns angle chasing into arithmetic.
You will find identity manipulation, equations over restricted domains, sums of trigonometric series, and problems where the trigonometric form is a disguise for something much simpler underneath.
Latest problems
37 problems
Cosine of a Doubled Arctangent
1167
1
Cosine of a Shifted Angle
1167
5
Trigonometric Value from a Given Sine
1167
2
An Endless Sum of Powers of Sine
1000
5
Fifth Powers of Sine and Cosine
1000
2
Trig Value from a Quadrant II
1000
2
Trigonometric Identity
1000
2
Sine Plus Cosine Scaled
917
1
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