Mathematics Level IC/IIC Subject Tests
191
ARCO
■
SAT II Subject Tests
w w w . p e t e r s o n s . c o m / a r c o
Solution: Since the sum of the degree measures of the interior angles of a triangle is 180:
45 + 55 +
PQR = 180
PQR = 180 – 100 = 80
Since
PQR =
x +
x:
2
x = 80
x = 40
Since
PQ and
ST are parallel,
x =
y, and
y = 40.
So the correct answer is
(B).
(NOTE: Level II does
not test plane geometry per se, so this is a problem that might appear on Level I, but
would not appear on Level II.)
Coordinate Geometry
EXAMPLE:
Which of the lines in the
above figure is the graph of y = –2?
(A) a
(B) b
(C) c
(D) d
(E) e
Solution: The graph of
y = –2 is a horizontal line with
y intercept –2. So the correct answer is
(A).
Solid Geometry
EXAMPLE:
If a cube has edges of length 1, what is the distance from any vertex to the center of the cube?
(A)
(B)
(C) 1
(D)
(E)
Lesson 8
192
w w w . p e t e r s o n s . c o m / a r c o
ARCO
■
SAT II Subject Tests
Solution: A figure will make the solution to the problem easier to understand:
The center of the cube lies on the hypotenuse of a right triangle
formed by an edge of the cube, a diagonal
of the face of the cube, and the diagonal of the cube itself. The diagonal of
the face of the cube forms a
right isosceles triangle:
Since the legs of the triangle have length 1, the hypotenuse has length 1
×
. Now we can calculate
the length of the diagonal of the cube using the Pythagorean Theorem:
Since the center of the cube lies at the midpoint of the diagonal of the cube,
the distance from any vertex
to the center of the cube is
. So the correct answer is
(B).
Trigonometry
EXAMPLE:
sin
2
(2
x) + cos
2
(2
x) =
(A) 0
(B) 1
(C) 2
(D) 4
(E) 4 sin
2
x
2
cos
x
2
The correct
answer to this item is (B): “sin
2
A + cos
2
A = 1” is one of the Pythagorean Identities.