A notch you cannot see

You are given the three orthographic views of a part, in THIRD ANGLE — check the arrangement before you read them. The views show a notch cut from one corner of the block. Find which corner, then decide whether you could see it from the front, the right and above. Draw the part as an ISOMETRIC drawing on the grid, seen from the front, the right and above: heights go straight up, widths and depths along the sloping lines, one grid step per unit. This is a pictorial, so leave hidden edges out entirely. Place the drawing anywhere with room around it.

The part, in three views

Third angle projection. Each square is one unit: count them to read the sizes off the views.

The method

Worked example: a plain block on isometric paper, with its three edge directions carried past the nearest corner: straight up, and 30° either side. It illustrates the method only, not this exercise's answer.

Line

Isometric drawing: hints

Three directions, and the grid already has them
Every edge of these parts runs along the part's width, depth or height, and each has its own direction on isometric paper: heights go straight up, widths slope at 30° down to the right, and depths slope at 30° up to the right. Those are exactly the grid's three families of lines, so every line you need is already ruled.
One grid step per unit, in every direction
This is an isometric DRAWING, so nothing is shortened. A part four units wide is four grid steps along a sloping line, just as a part four units tall is four steps up a vertical one. Count steps along the line, not squares across the page.
Where the faces go
You are looking from the front, the right and above. A face that points to the front shows its width edges rising to the LEFT; a face that points to the right shows its depth edges rising to the RIGHT; a face that points up shows both. Getting this backwards draws the part as seen from the front LEFT, which is a different drawing.
Leave hidden edges out
An isometric drawing shows the part as it looks, so an edge you could not see from the front, the right and above is simply not drawn — no dashed lines. Some features in the three views cannot be seen from that corner at all, and they do not appear in the drawing.
A straight edge is one line
Draw each straight edge as a single line from one end to the other, even where it runs past the corner of another face. Two half-lines that meet in the middle are marked as two wrong lines, not one right one.
Build it from the block
Lightly draw the block the part is cut from as construction lines, then draw the part inside it and cut the features away. Construction lines are never marked, so you can leave them in.

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