sat suite question viewer
The circle shown has center , circumference , and diameters and . The length of arc is twice the length of arc . What is the length of arc ?
Explanation
Choice B is correct. Since and are diameters of the circle shown, , , , and are radii of the circle and are therefore congruent. Since and are vertical angles, they are congruent. Therefore, arc and arc are formed by congruent radii and have the same angle measure, so they are congruent arcs. Similarly, and are vertical angles, so they are congruent. Therefore, arc and arc are formed by congruent radii and have the same angle measure, so they are congruent arcs. Let represent the length of arc . Since arc and arc are congruent arcs, the length of arc can also be represented by . It’s given that the length of arc is twice the length of arc . Therefore, the length of arc can be represented by the expression . Since arc and arc are congruent arcs, the length of arc can also be represented by . This gives the expression . Since it's given that the circumference is , the expression is equal to . Thus , or . Dividing both sides of this equation by yields . Therefore, the length of arc is , or .
Choice A is incorrect. This is the length of arc , not arc .
Choice C is incorrect and may result from conceptual or calculation errors.
Choice D is incorrect and may result from conceptual or calculation errors.