How to find the distance between two parallel lines?

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I'm trying to solve the following problem. I'm given few sticks of length [42, 40, 32, 30, 25, 18, 15] in this case. I'm able to construct three valid combinations of triangle. Now I need to calculate the distance between the lines (ie' the width occupied by all the triangles). One thing which strikes me is to find the height of each triangle - but I'm not able to proceed further.

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Some clue on this would be helpful please.

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Calculate the angles of triangles using the cosine rule, hence work out the distance of your point from the given line.

For example, in the left diagram, the triangle 25-30-32 the angle opposite 30 is $$ \cos^{-1}\frac{25^2+32^2-30^2}{2\cdot 25\cdot 32} $$ Similarly, the angle opposite 15 in 32-15-42 is $$ \cos^{-1}\frac{32^2+42^2-15^2}{2\cdot 32\cdot 42} $$ so the distance of vertex 15-42 from line 25 is $$ 42\sin\left(\cos^{-1}\frac{25^2+32^2-30^2}{2\cdot 25\cdot 32} -\cos^{-1}\frac{32^2+42^2-15^2}{2\cdot 32\cdot 42} \right). $$