Module 8 Oral Component Review

Module 8 Oral Component Review:

Please note that this is a brief list of topics to help you prepare for the Discussion Based Assessment and does not include every type of question you will find on the written test.

1)Be able to determine whether three segments can form a triangle.

a) 4 inches, 5 inches, 7 inches

b) 12 ft, 8 ft, 3 ft

c) 20cm, 40cm, 60cm

d) 55m, 90m, 45m

2) Be able to classify triangles by both angle measure and side length using the following classifications:

Classify triangles as acute, right, or obtuse using the angle measure.

Classify triangles as scalene, isosceles, or equilateral using side length.

3) What is a “regular” polygon?

4) Triangle Sum Property

a) The sum of the three angles of any triangle will add up to ______.

b) If a triangle has one angle measuring 32 degrees and a second angle measuring 55 degrees, find the measure of the third angle.

5) Polygon Sum Property

a) Write formula for the Polygon Sum Property.

b) Find the sum of the angles of a rectangle.

c) Find the sum of the angles of an octagon.

6) Similar Triangles

a) Which side corresponds to AB? To AC?

b) If AB = 12 and AC = 9, and if XY = 4, then find the measure of XZ.

7) Give triangle QRS and triangle DEF, which side in the second triangle corresponds to side QS?

8) Know how to solve a proportion using cross multiplying. Solve for x.

a) b)c)

Module 8 Oral Component Review Answer Key:

In a triangle, the sum of the lengths of two of the sides must be greater than the length of the third side.

a)4 + 5 > 7 so, the sides can form a triangle yes

b)3 + 8 < 12 so, the sides cannot form a triangle no

c)20 + 40 = 60 but is not >60 so, the sides cannot form a triangle no

d)45 + 55 > 90 so, the sides can form a triangle yes

a) 100 degrees is an obtuse angle; no sides are equal in measure is a scalene triangle

So the triangle is an obtuse, scalene triangle

b) the box is a right angle, two sides are equal in measure means it is an isosceles triangle

so the triangle is a right, isosceles triangle

3. What is a “regular” polygon?

All sides have the same length and all angles have the same measure.

4. Triangle Sum Property

a) The sum of the three angles of any triangle will add up to _____180 degrees______.

b) If a triangle has one angle measuring 32 degrees and a second angle measuring 55 degrees, find the measure of the third angle.

Let X be the unknown angle, so …… X + 32 + 55 = 180

X + 87 = 180

X + 87 – 87 = 180 – 87

X = 93 degrees

5. Polygon Sum Property

a) The formula for the sum of the angles in a polygon is , where n is the number of sides. (Note: It is easiest to type this formula as 180(n-2). A number in front of parenthesis means multiply.)

b) A rectangle has 4 sides so.….. 180(n-2)

180(4 – 2)

180(2) = 360 degrees

c) an octagon has 8 sides so….. 180(n-2)

180(8 – 2)

180(6) = 1080 degrees

6. Similar Triangles

a) Which side corresponds to AB? Side XYTo AC? Side XZ

b) Write the proportion with corresponding sides so,

We now cross multiply, 12 times S = 4 times 9

now, we solve the equation by dividing both sides by 12

thus, s = 3

7. Give triangle QRS and triangle DEF, which side in the second triangle corresponds to side QS?

First, write the names of the triangles with the angles that are equal in measure in the same order. I usually write the names one on top of the other so I see the angles that correspond.

Now you can see angle Q corresponds to angle D, angle R to angle E and angle S to angle F

It is also easy to see which sides correspond; QR corresponds to DE,(see the order) and RS corresponds to EF AND side QS would correspond to side DF.

8. Solve for x.

a) We cross multiply to get 9 times x equals 6 times 3

Now solve the equation by dividing both sides by 9

So x = 2

b)We cross multiply to get 6 times x equals 24 times 4

Now solve the equation by dividing both sides by 6

So x = 16

c) We cross multiply to get 32 times x equals 8 times 12

Now solve the equation by dividing by 32

So x = 3