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- 1). Draw a tangent to the curve at the point whose angle you want to calculate. This tangent must touch the line at just one point, and it must appear as close to the curve at either side of this contact point.
- 2). Identify the coordinates of two points on the tangent. For this example, imagine that two points have coordinates of (3, 8) and (6, 17).
- 3). Divide the difference between these points' y-coordinates by the difference between their x-coordinates: (8 - 17) ÷ (3 - 6) = 3. This is the tangent's slope, or gradient.
- 4). Use a scientific calculator to find the inverse tangent, or arctan, of this value. With this example: atan (3) = 71.57. This is the tangent's angle and the angle associated with the curve at the contact point.
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