sin(tan−121)
Figuring out the sin is no problem (use Pythagorean theorem), but how do you determine the sign of the answer. According to ASTC (acronym), tan is positive in the 1st and 3rd quadrants, yet the answer to this problem 55 is positive, and is shown to be totally in the 1st quadrant, not the 3rd. How do we know it is in the 1st and not the 3rd?
Figuring out the sin is no problem (use Pythagorean theorem), but how do you determine the sign of the answer. According to ASTC (acronym), tan is positive in the 1st and 3rd quadrants, yet the answer to this problem 55 is positive, and is shown to be totally in the 1st quadrant, not the 3rd. How do we know it is in the 1st and not the 3rd?
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