This is a free lesson from our course in Geometry

 This lesson introduces and walks you through the basic concepts about the trigonometric functions and right triangle and their relationship. You will learn it with the help of some examples and practice questions with solution, using video and explanations in own handwriting by the instructor that brings in an element of real-class room experience.(More text below video...)
Other useful lessons:
 The Tangent Ratio Inverse Tangent Inverse Sine and Cosine Angles of Elevation and Depression - Geometry
(Continued from above)The values for the trigonometric functions are defined as the value that you get when divided one side by the other side i.e. ratio of one side to the other. E.g. sin x = opposite/hypotenuse. Further you'll look into how you can use the ratios of side-length of right triangles to determine the measures of sides and angles. We'll use the Pythagorean Theorem, concept of ratio and properties of sines, cosines, and tangents to solve the triangle, that is, to find unknown parts in terms of known parts. E.g. In a right triangle ABC, with sides a, b and c, you need to remember:
• Pythagorean Theorem: a2 + b2 = c2
• Sines: sin A = a/c, sin B = b/c
• Cosines: cos A = b/c, cos B = a/c
• Tangents: tan A = a/b, tan B = b/a
Now let us first find solution of a problem where we don't know the hypotenuse but we do know the other two sides. Then proceed using the Pythagorean Theorem, and that give us the hypotenuse. For example: if a = 10 and b = 24, then
c2 = a2 + b2 = 102 + 242 = 100 + 576 = 676.
The square root of 676 is 26, so c = 26.
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