SAT Mc Graw Hill 2011

(Marvins-Underground-K-12) #1

  1. B The length of the garden is p.The width is
    half of 44 −p.Therefore, the area is p((44 −p)/2) =
    (44p−p^2 )/2.

  2. E You get the maximum number of pieces (11)
    by making sure that each cut intersects every
    other previous cut in a new spot. Your diagram
    should look something like this, with six points of
    intersection in the circle.

  3. B Draw the extra line shown here to see that the
    shaded region has a perimeter equal to a 10-by-17 rec-
    tangle. Therefore its perimeter is 10 + 17 + 10 + 17 =54.


3


10


20


17


  1. A Move the pieces together to see that they
    form a right triangle. Since all of the interior an-
    gles of an equilateral triangle are 60°and the
    bisectors divide them in half, the triangle is a
    30 °-60°-90°triangle, so its base must be , and
    the area is ()()232 2 23() =.


23


2


2 √ 3

30 °


  1. E The two right triangles have two pairs of equal
    sides (the two radii and the shared hypotenuse),
    so they must be congruent triangles. Arc BDis^1 ⁄ 3
    of the circle, with circumference 12π. Therefore,
    you should be able to determine the measures
    shown in this diagram and see that the perimeter
    of the shaded region is 12 3 4+ π.


A


B


C


D


° 1230
30 °

60 °
60 °

6

6 √ 3 6

6 √ 3


  1. A If the circle has an area of 4π, its radius is 2. If
    the rectangle has an area of 8, its length must be
    4. The arc portion of the shaded region is^1 ⁄ 4 of
    the circle with circumference 4π, so the perimeter
    is 2 + 2 + 4 +π= 8 +π.


P


R


(^22)
4
2 2
π
388 McGRAW-HILL’S SAT



  1. 81 or 100 Consider the right triangle in the
    upper-left corner of the diagram. Notice that it
    has a hypotenuse of aand legs of length band
    12 −b. The question is asking for the area of the
    shaded square, which is a^2. By the Pythagorean
    theorem, a^2 =b^2 +(12 −b)^2 = 2 b^2 − 24 b+144. Since
    2 b 5, the maximum possible value of a^2 is
    2(2)^2 −24(2) + 144 =104, and the minimum pos-
    sible value of a^2 is 2(5)^2 −24(5) + 144 =74. Since
    amust be an integer, a^2 must be a perfect square,
    and the only perfect squares between 74 and 104
    are 81 and 100.


12


12 - b

a

b
b
Free download pdf