Lengths of subtangent and subnormal (Subtangentlength=|y0/f'(x0)|;subnormal=|y0f'(x0))
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Subtangent length = |y0/f'(x0)|; subnormal = |y0 f'(x0)| (standard Cartesian at P(x0,y0) on y=f(x))
What each symbol means
| Symbol | What it stands for |
|---|---|
| y_0 | Ordinate of point |
| f'(x_0) | Slope of tangent (nonzero for subtangent formula) |
When to use this
Cartesian curve y=f(x); for subtangent need f'(x0)≠0; lengths are positive.