A lesson challenges scholars to create a cinquain poem. Writers begin by choosing a topic and brainstorm details, then compose their original poem making sure to count syllables. 

Learners use the sum angle formula for sine to derive the sum and difference formulas for cosine and tangent. The level of difficulty is quite high. Learners must be familiar with trigonometric identities as well as the characteristics...

This site from the University of Saint Andrews provides an historical look at the origins of trig functions. This site ties together mathematics and history from Hipparchus to Ptolemy to Lambert.