Warm – up for 9.5
Simplify.
1. 900n5
2.  2 121x3 y
3. A square has a diagonal of 12. Find the
length of a side and find the area of the
square.
(draw the picture and use the
Pythagorean Theorem)
Answers
1. 30n
2
n
2.  22 x xy
3.
side length is
6 2
and area is 72
9.5 Coordinate Geometry
• Distance Formula
Distance Between Two Points =
 x2  x1    y2  y1 
2
2
1) Find the distance between the points.
(5,8) & (-4,-4)
Distance formula=
 x2  x1    y2  y1 
2
4  5)
Plug in the
values and
simplify
9)
2

81  144
225
15
2

2
4  8)
12)
2
2
2) Find the distance between the points.
A(8,15) and B(-7,23)
Distance formula=
 x2  x1    y2  y1 
2
7 8)  (23 15)
2
2
15)  (8)
2
2
225  64
289
AB = 17
2
Try these on your own:
3. (10, 20) and ( 13, 16)
4. (5, -2) and ( 7, -9)
5. (0, 0) and ( -8, -10)
3.
5
4.
53
5.
2 41
6. Identify the Triangle with the points
A(3,-5), B(5,-1), C(7,-3) as
Scalene, Isosceles, or Equilateral.
Hint: Draw the triangle, then find the
distance between A&B, B&C, A&C.
AC  2 5
BC  2 2
AB  2 5
Triangle ABC is Isosceles
7. Find the perimeter of triangle ABC
with vertices
A(2, 4), B(8, 12), C(24, 0).
AB = 10, BC = 20, AC = 10 5
perimeter  30  10 5
8. Determine whether triangle ABC with
vertices A(6, -6), B(39, -12), C(24,
18) is scalene, isosceles, or
equilateral.
isosceles
Classwork: p. 489 #1-6 OR Factoring
Game
Homework: WS 9.5