SAT数学练习题答案解析Question 7:
Answer: If l is the side of the cube, the volume of the cube is: Vcube = l3.
The volume of the sphere is Vsphere = 4?r3/3 = 4?(l/2)3/3 = (?/6)l3
Vcube/Vsphere = 6/?
SAT数学练习题答案解析Question 8:
Answer: tan(2x) = 2tan(x)/(1 - tan2(x))
2 = 2tan(x)/(1 - tan2(x))
tan(x) = 1 - tan2(x)
tan(x) = (1 - tan(x))(1 + tan(x))
SAT数学练习题答案解析Question 9:
Answer:
BC2 = AB2 + CA2 - 2·AB·CA·cos(a)
112 = 52 + 72 - 2·5·7·cos(a)
121 = 25 + 49 - 70cos(a)
cos(a) = -47/70
a = arccos(-47/70) = 132.2o
SAT数学练习题答案解析Question 10:
Answer:
a + 3 = k(a - 1)
3a + 1 = k(a + 3)
(a + 3)(a + 3) = (3a + 1)(a - 1)
a2 + 6a + 9 = 3a2 - 2a - 1
2a2 - 8a -10 = 0
a2 - 4a -5 = 0
the solutions of this equation are 5 and -1. The only positive solution is 5, so the progression is 4, 8, 16. The fourth term will be 16·2 = 32
要想SAT2数学成绩有所提高，坚持每天做练习是十分必要的，就像这样每天完成SAT2数学Level 2练习题，并进行总结，日积月累，成绩就会有明显地提高。
