<p>Page 76, questions 14,15,16</p>
<p>For question 14 I got the answer to be 6 pi although the answer keys says its 12 pi.</p>
<p>For Question 15 I eliminated A,D,E but dont know about B and C Is there an easier way to solve this rather than just try numbers?</p>
<p>For question 16 I eliminated 7 and 8 as they are bigger than 36.</p>
<p>Please help me and tell me how you solved it.</p>
<p>Q14: its 12pi, use the circumference = diameter x pi formula
Q15: Answer is C because B holds for -1<x<0
Q16: CP must be shorter than BC, which is 3, so the answer is A, 2.</p>
<ol>
<li><p>We can see that the larger circle’s circumference is divided in half and that one of the halves should be included in our calculation. The larger circle has radius 6 (2*3). So, half of the circumference is 0.5 * (2pi * 6) = 6pi. We must also include half of the circumference of each smaller circle, or the whole circumference of one of them. That calculation is just 2pi * 3 = 6pi. Add the two up and we get 12pi. If you didn’t get any of that, I can prove it. Just say the word…</p></li>
<li><p>You don’t necessarily need to try an actual number; just consider possible ranges. Looking at B and C (the two options not immediately dismissed), we can see that a negative number within the domain -1 < x < 0 would make B true - raising it to an even power will make it positive, while an odd power over one will make it a greater negative. So, C is the right answer.</p></li>
<li><p>Drawing CP perpendicular to AB would make two smaller right triangles. One of the triangles has CP as a leg and BC as the hypotenuse. The length of the hypotenuse must be greater than the length of either leg, so CP < BC. If BC is 3, the only choice smaller is 2. The answer is therefore A.</p></li>
</ol>
<p>14, the total perimeter includes a half big circle’s and a whole small circle’s,thus, it’s 2pi<em>r+pi</em>R=6pi+6Pi=12pie, since you can infer that the big circle’s radius is 6.
15, C. let’s see B, if x is a negative number it will be wrong. I think trying numbers is the best way but don’t miss any possible situations.
16, i suppose it’s A, since in the picture we know that it’s not an abstuse nor a right triangle, thus the height should be shorter than BC, thus only A is possible.</p>
<p>Thank you all for responding. I have understood all the answers</p>
<p>For question 14 I got mixed up between area and perimeter
For question 15 I dont know how I didnt solve it right
For question 16, I immediately knew the answer after I typed the questions here</p>
<p>All careless mistakes!!! I have no idea how I will get an 800 in maths with all these mistakes…Oh well 11 more maths exams to go, hopefully I will learn.</p>