SOF International Mathematics Olympiad (IMO)
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IMO Level 1
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2026
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Sample
Simplify: sin 70° / cos 20°
Explanation
Explanation
Since 70° and 20° are complementary angles (they add to 90°), sin 70° = cos 20° (co-function identity: sin θ = cos(90° - θ)). So sin 70° / cos 20° = 1.
PRO TIP
Re-check your working by substituting the answer back into the original question.
Related Questions
The average of 5 numbers is 18. If one of the numbers, 12, is removed, what is the average of the remaining numbers?