In the given triangle, find the
value of x, and the m<ABC.
In the figure shown below, segment BD bisects
segment AC, and segment AB is congruent to
segment BC.
 Prove that triangle ADB and triangle CDB
are right triangles. Use a two-column
proof.
 The area of the triangle is
equal to the area of the
parallelogram.
What can you
conclude about the
area of the two
shapes?
Area of triangle Area = ½ (B x H)
Area of
parallelogram
Area = B x H
The segment joining the midpoints of two
sides of a triangle is parallel to the third
side and is half as long as the third side.
Midline
Theorem
Example 1:
Find the
value of x.
B is the midpoint of segment AC, D is the
midpoint of segment CE, and AE = 17.
Find BD.
Example 2:
a. If AC = 10 and AB = 16, find
AD, BE, and DE.
b. If AC = x - 10 and DE = 6, find
the value of x.
ABC is an
isosceles
triangle
with base
AC and
midline DE.
Find the
value of x,
y, and z.
x = ___ AB = ___
y = ___ AC = ____
z = ___ CB = ____
m ABC = _____ m DEB = _________
m ADE = _______m EDC = _________
m ACB = _______
D is the midpoint of segment AC, E is the
midpoint of segment AB.
Write Summary
 At least 3 sentences
1. ABC is an isosceles triangle with
base and midline
If AC = 10 and AB = 16, find:
AD = _______ BE = ______
DE = _______
2. If AC = x – 10 and DE = 6, find the
value of x.
E
D
A
B
C

Grade 9 Mathematics 3rd Quarter Midline Theorem.ppt

  • 1.
    In the giventriangle, find the value of x, and the m<ABC.
  • 2.
    In the figureshown below, segment BD bisects segment AC, and segment AB is congruent to segment BC.  Prove that triangle ADB and triangle CDB are right triangles. Use a two-column proof.
  • 5.
     The areaof the triangle is equal to the area of the parallelogram. What can you conclude about the area of the two shapes? Area of triangle Area = ½ (B x H) Area of parallelogram Area = B x H
  • 6.
    The segment joiningthe midpoints of two sides of a triangle is parallel to the third side and is half as long as the third side. Midline Theorem
  • 7.
  • 8.
    B is themidpoint of segment AC, D is the midpoint of segment CE, and AE = 17. Find BD. Example 2:
  • 9.
    a. If AC= 10 and AB = 16, find AD, BE, and DE. b. If AC = x - 10 and DE = 6, find the value of x. ABC is an isosceles triangle with base AC and midline DE.
  • 10.
    Find the value ofx, y, and z.
  • 11.
    x = ___AB = ___ y = ___ AC = ____ z = ___ CB = ____ m ABC = _____ m DEB = _________ m ADE = _______m EDC = _________ m ACB = _______ D is the midpoint of segment AC, E is the midpoint of segment AB.
  • 12.
    Write Summary  Atleast 3 sentences
  • 14.
    1. ABC isan isosceles triangle with base and midline If AC = 10 and AB = 16, find: AD = _______ BE = ______ DE = _______ 2. If AC = x – 10 and DE = 6, find the value of x. E D A B C