Math Gold Medalist

Lor

2023 AMC 12A 

Problem 11

What is the degree measure of the acute angle formed by lines with slopes $2$ and $\tfrac{1}{3}$?

$\textbf{(A)}~30\qquad\textbf{(B)}~37.5\qquad\textbf{(C)}~45\qquad\textbf{(D)}~52.5\qquad\textbf{(E)}~60$

Important Trigonometry Formulas

Important Coordinate Geometry Formulas

tan(a)=2

tan(b)=1/3

tan(a-b)=1

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   Solution