The second choice is correct. Given that angle 2 and angle 6 are congruent, the largest in each of the corresponding triangles are vertical angles meaning that two known angles are known in each triangle (and they are equal) which means that the last "unknown" (angles 3 and 7) are congruent. The lines DC and AB correspond with these defined, congruent triangles meaning they are parallel.
Answer:
20 meters
Step-by-step explanation:
The shadow of the building will look like a right triangle. In this problem, the hypotenuse of the triangle is 25 meters, and one of the sides is 15 meters. What we are trying to find is the length of the other side.
We can do this by using pythagoreans theorem.

So, the last side (or the height of the building) is 20 meters.
2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97
D) 1.2
Add up all the numbers then divide by how many numbers there are