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Course web for the Spring 2019 Computer Graphics Class

Mistake in Workbook 5

A student pointed out that in the original version of Workbook 5, what I said was a 5, 12, 13 triangle really was a 25,120, sqrt(25^2+120^2) triangle. Sorry about that. I have fixed it.

If you did your import after about 10pm on Monday, you will not see this problem – I have fixed it.

If you imported workbook 5 before about 10pm Monday, you will see this problem.

If you have the broken version you can:

1. either copy or pull a new version of 4-arclength.html and 4-arclength.js from

2. edit the files as follows:

change the line in 4-arclength.html so that the “arcex” canvas has height 140 (not 90)
change lines 102 and 103 in arclength.js to be 10+50 for y (instead of 10+25)
change lines 130 and 131 in arclength.js to be 10+50 for y (instead of 10+25)

(warning: there was initially a typo – it is 10+50 not 10+10).


3. just solve the problem for the shorter triangle.