The Algebra of Co-planar Vectors and Trigonometry. By R. Baldwin Hayward, Senior Mathematical Master in Harrow School, formerly Fellow of St. John's College, Cambridge.

Revise topics such as angles, lines and polygons, loci and constructions, circles, sectors and arcs, transformations, Pythagoras' theorem, trigonometry and vectors.

Understanding how to convert between degrees and radians is one of the most crucial skills for anyone studying trigonometry, calculus, or advanced mathematics.