PPLATO, Promoting Physics Learning & Teaching Opportunities has a basic mathemetics Ebook that teaches Trigonometry. This is provided by the University of Plymouth
Trig seems to be a lost subject these days for highschoolers, with most school systems now teaching Algebra 2 and intro to Caluclus. But should your child want to learn trig, this website will help you.
Get extra Trig Help by using Trigonometry For Dummies (For Dummies (Math & Science))
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