G21's exact values, both tiers: sin and cos at 0, 30, 45, 60 and 90 degrees, and tan at 0, 30, 45 and 60 only — tan 90 is undefined and outside G21. Derive from the half-equilateral and right-isosceles triangles for non-calculator questions. Surd arithmetic support is Number's N8. (G21)