# What algorithm or formula can it be ascertained whether the point between the parallel straight?

• There are two parallel straight equations:

a1x + b1y + c1 = 0
a2x + b2y + c2 = 0.

How to determine whether the P(x, y) point is between them?

• For example, this is how:

Let `n` - the general vector normalized your direct, `A1` and `A2` - 1st and 2nd straight points, respectively `X` - Checkpoint. Calculate the scalary works `(XA1, n)` and `(XA2, n)`♪ The point lies inside if these works have the opposite sign.

Not necessarily parallel direct and stupid corner, we' corner. two Normal vector `n1` and `n2`♪ Then the following values should be established: `isFirstDirectionPositive` - the sign of the polar work `(XA1, n1)` (respectively, the result of the setting of the point in the first straight equation), `isSecondDirectionPositive` - the sign of the polar work `(XA2, n2)` (respectively, the result of the point set in the second straight equation) and `isAngleBetweenNormalsAcute` - the sign of the polar work `(n1, n2)`♪ You need a piece of work. All three The signs were positive.

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