SAT Question 2bddbc1b: Right Triangles And Trigonometry answer and explanation with Desmos solution

Choice B is correct. The cosine of an acute angle in a right triangle is defined as the ratio of the length of the leg adjacent to the angle to the length of the hypotenuse. In the triangle shown, the length of the leg adjacent to angle $A$ is $41$, and the length of the hypotenuse is $42$. Therefore, $\cos A=\frac{41}{42}$.