So anytime we have a slope and want to find the slope of a perpendicular line, we just have to remember a perpendicular line's slope is the negative reciprocal (reciprocal means flip the fraction). So if we had a slope of 3/4, the slope perpendicular to it would be - 4/3.
First we need to find our slope, to do this we take the change in y over the change in x like so:
(15-12)/(4-7) = - 3/4
The slope perpendicular to this is 4/3.
None. there are always 2 acute angles in a 90 degree triangle
A mean is an average of a total. If you add all the pets together and divide by the number of people, you get the mean. So 1 +3 + 2 + 4 + 0 = 10
You have 10 pets in total.
There are 5 people.
Mean = 10 pets / 5 people = 2 pets per person. that's the mean or average that everyone has.
Notice that
(1 + <em>x</em>)(1 + <em>y</em>) = 1 + <em>x</em> + <em>y</em> + <em>x y</em>
So we can add 1 to both sides of both equations, and we use the property above to get
<em>a</em> + <em>b</em> + <em>a b</em> = 76 ==> (1 + <em>a</em>)(1 + <em>b</em>) = 77
and
<em>c</em> + <em>d</em> + <em>c d</em> = 54 ==> (1 + <em>c</em>)(1 + <em>d</em>) = 55
Now, 77 = 7*11 and 55 = 5*11, so we get
<em>a</em> + 1 = 7 ==> <em>a</em> = 6
<em>b</em> + 1 = 11 ==> <em>b</em> = 10
(or the other way around, since the given relations are symmetric)
and
<em>c</em> + 1 = 5 ==> <em>c</em> = 4
<em>d</em> + 1 = 11 ==> <em>d</em> = 10
Now substitute these values into the desired quantity:
(<em>a</em> + <em>b</em> + <em>c</em> + <em>d</em>) <em>a</em> <em>b</em> <em>c</em> <em>d</em> = 72,000
