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Trigonometry: SOH CAH TOA
Chapter summary, hard words and model exam answers for ICSE Class 10 Hindi.
Free online summary and notes (ICSE Class 10 Hindi). Read it here, no PDF download needed.
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Mathematics · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)
Summary
Hypotenuse is the longest side, opposite the right angle. Opposite and adjacent are named relative to the angle you choose, so they swap if you switch angle.
Circle the side you know and the side you want. SOH CAH TOA tells you which ratio uses exactly those two.
If the unknown is on top, multiply (opp = hyp × sin theta). If it is on the bottom, divide (hyp = opp / sin theta).
Write sin theta = 4/7, then theta = sin⁻¹(4/7). Check the answer is between 0 and 90 degrees.
Hard words & meanings
| Hypotenuse | the longest side of a right triangle, opposite the 90° angle |
| Opposite | the side directly across from the chosen angle |
| Adjacent | the side next to the chosen angle that is not the hypotenuse |
| Sine | the ratio opposite / hypotenuse for an angle |
| Cosine | the ratio adjacent / hypotenuse for an angle |
| Tangent | the ratio opposite / adjacent for an angle |
| Inverse function | sin⁻¹, cos⁻¹ or tan⁻¹: takes a ratio and returns the angle |
| Angle of elevation | angle measured upward from the horizontal to an object above |
Model exam answers, grammar & audio
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