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Which pair of formulas converts a polar point into rectangular coordinates?
Ax is r sin theta, y is r cos theta
Bx is r plus theta, y is r minus theta
Cx is r over theta, y is r times theta
Dx is r cos theta, y is r sin theta
Answer & Solution
Correct answer: D. x is r cos theta, y is r sin theta
1. Drop a perpendicular from the point to the x-axis to form a right triangle.
2. The cosine of theta is the adjacent side over the hypotenuse, so x is r cos theta.
3. The sine of theta is the opposite side over the hypotenuse, so y is r sin theta.
_Source: OpenStax Precalculus (CC BY 4.0), Ch 8 "Further Applications of Trigonometry", section 8.3 Polar Coordinates_