Sat math questions from blue book

<p>Test 1</p>

<p>Question 19 page 401 section 3.</p>

<p>I modified the square root as powers coz there is no SQRT button in pc.</p>

<p>19)The pyramid shown above has altitude h and a square base of side m. The four edges that meet at V, the vertex of the pyramid, each have length of e. If e = m, what is the value of h in terms of m?</p>

<p>1)m / (2^1/2)
2)m(3^1/2) / 2
3)M
4)2m / (3^1/2)
5)m(2^1/2)</p>

<p>How can we solve this ? I imagined this as pythogrean theorem problem since e = m,then the hyptonuse is equal = m,but the smaller leg we don't know its size how can we calculate this then ? We don't know this is specail triangle or anything.</p>

<p>Test 2
Question 17 page 456 section 2</p>

<p>17) The equation of the line above is y = -2x + 6. Which of the following is the graph of
y = |-2x + 6| ?</p>

<p>I solved this by plotting points but took most of my time for other questions is there a faster way to solve this question in order to do it fast on exam :D,because this took like 2 min to solve the slow way.</p>

<p>Thanks alot guys.</p>

<p>For 17, just use logic. Since y equals the absolute value of the equation above, that means that y can’t be negative. That eliminates choices A,C, and E. You’re left with choices B and D, and if you look for the x-intercept, you’ll see that the answer is B.</p>

<p>For 19, you’re very close to figuring it out. You need the smaller leg. Look at the base of the pyramid. It’s a square with side m. The smaller leg is 1/2 the diagonal of the base. Apply the Pythagoras theorem to the base to figure out the size of the diagonal: d<em>d = m</em>m + m*m. So d =sqrt(2) * m. The smaller leg is then half of that or 1/2 * sqrt(2) * m.</p>

<p>Back to the the right triangle with hypotenuse e=m: m<em>m = h * h + 1/2 * m</em>m, and you get h<em>h = 1/2 m</em>m or h = (1/sqrt(2))*m</p>

<p>@PencilxBoxes thanks alot should have thought abt this thanks.</p>

<p>@Fogcity Thanks alot this made perfect sense :).</p>

<p>17) When you take the absolute value of a positive number, you just get that number back. Graphically this means that all points above the x-axis DON’t CHANGE.</p>

<p>When you take the absolute value of a negative number, you change it to the corresponding positive number. Graphically this means that all points below the x-axis are reflected above the x-axis.</p>

<p>So to graph the absolute value of a function, just reflect the part that is below the x-axis in the x-axis, and leave the rest where it is.</p>

<p>For 19 I understand up to getting the smaller leg but I don’t understand the Pythagoras theorem for the right angle. What happened to the sqrt(2) for the smaller leg?</p>