## relation between arc, radius and central angle. Proof of the trigonometrical ratios of complementary angles

Relation between arc radius and angle     Arc length   =   [radius • central angle (radians)] Arc length   =   circumference • [central angle (degrees) ÷ 360]     Proof of the trigonometric ratios of complementary allied angles Two acute angles are complementary to each other if their sum is equal to 90°. In a right … Read more

## area of triangle, condition of co-linearity of three points. Trigonometry – Measure of angles in the sexagesimal. contesimal and circular systems

Area of triangle The area of triangles can be found by using the following formula:   Area =  Base × height / 2 The red line represents the length of the base (call it b if you want) and the blue line represents the length of the height. To get the area, just multiply the value … Read more

## Distance between two points,proportional division of a line (section formula)

Distance between two points Here is how to calculate the distance between two points when you know their coordinates:     Let us call the two points A and B     We can run lines down from A, and along from B, to make a Right Angled Triangle. And with a little help from … Read more

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