Explanation
Correct answer: A.
Choice A 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 that angle to the length of the hypotenuse. It's given that angle is a right angle in triangle and that angle F is a right angle in triangle . Therefore, is equal to the ratio of the length of side to the length of side , and is equal to the ratio of the length of side to the length of side . It's also given that triangle is similar to triangle , where angle corresponds to angle . Since similar triangles have proportional side lengths, . Therefore, the value of is equal to the value of . Since , the value of is .
Desmos solution:
Note: In similar right triangles, corresponding acute angles have equal cosine values, so cos E = cos B = 1/22.
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice B
Choice B is incorrect and may result from conceptual errors.
Choice C
Choice C is incorrect and may result from conceptual errors.
Choice D
Choice D is incorrect and may result from conceptual errors.