Explanation for Question 24 From the Math (Calc) Section on the Official Sat Practice Test 1
For number 24 were asked, which of the following is an equation of a 2 circle with the center at zero comma four and a radius endpoint at, 3 uh, four thirds comma five. So the first thing that we should worry about 4 here is our center or X coordinate zero. 5 And our Y coordinate is four. And so the general formula for the equation 6 of the circle is X minus H squared. 7 Plus Y minus K squared is equal to the radius squared. 8 So we can see that H is going to be our X coordinate of 9 the center, and K is going to be the Y coordinate of our center. 10 So if the X coordinate is zero, then what we're really doing here is 11 X minus zero squared, 12 which is just X squared. So that's why all of these just have an 13 X squared to begin with. Now, 14 if we look at this part, the Y minus K squared, 15 we see that our K is going to be four. 16 So what we need is why am I as four squared? You might be 17 tempted to do a Y plus four, because this four is positive. 18 But whenever you make the equation of the circle, you actually need to flip 19 the sign that's on your X and your Y coordinates. 20 So even though this says positive four, we want to choose one that says 21 negative four. So now we're here and we're just trying to figure out, 22 is it 25 over overnight? Or is it five over three? 23 And the way that we do that is by finding the radius, 24 we can do that kind of by drawing out a 25 coordinate plane. And we know that we're starting at 0 4, 2, 3, 4. 26 So our center is right h...