The Elements of Plane Trigonometry

a b c A+ B A B a+b+c AB² angle ACB angle of elevation b² c² BC² centre circumference cos A cos cos² cos³ cosec cosine cot A cot cot2 decimals diameter distance Divide equation equilateral feet formula given height hence hexagon inscribed circle log a log logarithms nth root number of sides P₁ perimeter perpendicular plane triangle quadrant radii radius ratio regular polygon right angle sec² sin A sin sin sin sin sin¹ sin2 sin² 18 sin³ sine sine and cosine square subtend subtracted tan-¹ tan¹ tan² tangent triangle ABC unity whole number