**The Official SAT Subject Test in Mathematics Level 1 Study Guide: Test 1**

The playlist below organizes the video explanations to the 50 questions from practice test 1 in The Official SAT Subject Test in Mathematics Level 1 Study Guide. This is one of the two new tests that are part of this Official SAT Subject Test in Mathematics Level 1 Study Guide released in September 2017.

Md Sohazur Islam Sozib says

The should be 3.5 as the midpoint of the diameter is D. So, AD=CD=BD=2.5 as they all are the radius (half of the diameter ,which is equal to 5.). Then triangle ABD is a isosceles right triangle whose area is equal to 2.5. That concludes triangle BCD’s area is 3.5.

I hope this makes sense.

Dabral says

Thanks for the comment, it made me realize that there is a shorter method.

Question 43: Actually the area of the two triangles ABD and BDC are equal because they both share the altitude and the bases are equal (AD=DC=3=radius). I did it the long way by finding out the altitude which is not necessary. Instead, we know the area of triangle ABC which is 6, and because both triangles ABD and BDC have equal area, the area of triangle BDC is 3.