Reference Section > Shape Library > Triangles

The Filleted Triangle is a triangle defined by the lengths of its three sides, with the same fillet radius on all three corners. Because it is defined by side lengths rather than angles, it can be acute, right-angled or obtuse. Use it for triangular plates and gussets where the corners must be rounded.

It appears in the shapes library under Triangles.

Insert point and direction

The Bottom side lies along the X axis and runs in +X from the insert point. The insert point is the bottom left corner of the sharp triangle, that is the point where the Left side and the Bottom side would meet with no fillet. The Left side runs from the insert point to the top corner. The Right side runs from the right end of the Bottom to the top corner.

The top corner is where the Left and Right lengths meet. It is above the Bottom side, so Y is positive. Its X position depends on the sides: with the default sides it lies beyond the right end of the Bottom, and when the square of Left plus the square of Bottom is less than the square of Right it lies to the left of the insert point.

When Fillet R is greater than 0 the corners are rounded, so the insert point is not on the material. It is the theoretical sharp corner, outside the bottom left fillet.

The outline is one closed path, built in this order: the bottom left fillet, the Bottom side (left to right), the bottom right fillet, the Right side, the top fillet, then the Left side back down to the start. With a positive Bottom the path runs anticlockwise.

The Bottom, Left and Right dimensions are drawn between the sharp corners, not between the ends of the fillets. The Fillet R dimension is drawn on the bottom left fillet.

Properties

Property	Description	Default
Left	Length of the Left side, from the insert point to the top corner, measured between the sharp corners (length, mm or inch). The sign is ignored: the geometry uses the square of the length.	125 mm (5 in)
Right	Length of the Right side, from the right end of the Bottom to the top corner, measured between the sharp corners (length, mm or inch). The sign is ignored: the geometry uses the square of the length.	100 mm (4 in)
Bottom	Length of the Bottom side, along X from the insert point, measured between the sharp corners (length, mm or inch). Must not be 0.	50 mm (2 in)
Fillet R	Radius of the fillet on each of the three corners (length, mm or inch). The same radius is used on all three. Minimum 0; 0 gives sharp corners.	6.25 mm (0.25 in)

Limits

•The three sides must be able to form a triangle: Left must be shorter than Right plus Bottom, and so on for each side. Enter positive lengths. Negative values for Left and Right are not rejected; only their squares are used, so the triangle is the same as for the positive value. A negative Bottom is not rejected either: the triangle is then built to the left of the insert point.

•If the sides are collinear (one side equals the sum of the other two) the height is 0 and the triangle is flat. The shape does not check for this. Rounding can make the height calculation fail, in which case the shape shows as cannot be built (see below); otherwise it is drawn flat without an error. Check the drawing.

•Fillet R is not checked against the size of the triangle. The largest fillet that fits is the radius of the circle that touches all three sides (the inscribed circle); at that radius the straight sides shrink to nothing. A larger Fillet R can give an outline that crosses itself, and no warning is shown, so check the drawing when using a large fillet on a small or narrow triangle. With the default sides the largest fillet is about 17.3 mm (0.68 in).

When the shape cannot be built

If the values cannot make a valid shape, the outline is not rebuilt from the new values (the last outline that could be built stays drawn), a broken-shape marker is shown at the insert point, and the property page shows Warning: Cannot build shape from these parameters. This happens when:

•the Left, Right and Bottom lengths cannot form a triangle (one side is longer than the other two together), so there is no point where the Left and Right sides meet;

•Bottom is 0.

Every 2D shape also has the Transform properties (Base X, Base Y, Rotation, Scale, Mirroring X) and the Polar Array properties, listed after the shape's own properties.