Question

Geometrically proves of sin(-A) = -SinA​

Answer 1

Answer:

don't know sorry pls ask easy question

Answer 2

Answer:

How do I prove sin (90+A) = cosA geometrically?

You have a right triangle ABC, with right angle at B, hypotenuse AC of length 1, AB of length cos A. Construct the square ACDE (vertices lettered counterclockwise) and drop a perpendicular from E to the leftward continuation of AB, intersecting at F. Now AFE is congruent to ABC because AE is also length 1 and the angle FAE is 90 degrees minus CAB and therefore equal to BAC. Side EF which is by definition sin(90+A) is therefore equal to AB.

Step-by-step explanation:

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