Three lines make a triangle

Challenge 7 of 13

Three lines can enclose a shape, but only if their ends meet exactly — a gap of a few pixels shows. Two sides are drawn here. The third has to run from the bottom-left corner back up to the top.

Set its four numbers.

Your code JavaScript

Set its four numbers.

Console print() output

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Lesson Lines & Triangles

A line is not placed like the other shapes. It is drawn between two points, so it needs four numbers: line(x1, y1, x2, y2); The first pair is where it starts and the second pair is where it ends.

That is more numbers at once than you have typed before, so here is the way to do it: one point at a time. Set the first two numbers until the start of the line is in the right place, press Run, and then fix the other end. You do not have to get all four right together, and Reset will always put the starting numbers back.

If nothing appears at all, check whether both ends are still at the same spot — a line from a point to itself has no length to show.

Three lines can enclose a shape, but their ends have to meet exactly, and each corner ends up typed twice. A triangle does the same job in one command: triangle(x1, y1, x2, y2, x3, y3); — six numbers, a pair for each corner, and the ends are always joined for you.

A dot is the other extreme: dot(x, y); is a single point, just two numbers. It has no length and no inside, so its size comes from outlineThickness — a thick pen draws a fat dot.

Lines, triangles and dots are drawn with the outline pen, so outlineColour and outlineThickness are what make them visible. A triangle is still a shape, though, so shapeColour fills it in and noShapeColour leaves it hollow.

Grid helps here more than anywhere else in the course.