Section 7.3 Triangles

287

Tell whether x and y show direct variation. Explain your reasoning.

If so fi nd the constant of proportionality.

(Section 5.6)

28.

x = 2y

29.

y x = 6

30.

xy = 5

31.

MULTIPLE CHOICE A savings account earns 6% simple interest per year. The

principal is $800. What is the balance after 18 months?

(Section 6.7)

A

$864

B

$872

C

$1664

D

$7200

Draw a triangle with the given angle measures. Then classify the triangle.

14.

15 75 90

15.

20 60 100

16.

30 30 120

Draw a triangle with the given description.

17.

a triangle with a 2-inch side and a 3-inch side that meet at a 40 angle

18.

a triangle with a 45 angle connected to a 60 angle by an 8-centimeter side

19.

an acute scalene triangle

20. LOGIC You are constructing a triangle. You draw

90

90

80

100

70

110

60

120

50

130

40

140

30

150

20

160

10

170

0

180

100

80

110

70

120

6

0

13

0

5

0

140

40

150

30

160

20

170

10

180

0

35

the fi rst angle as shown. Your friend says that you

must be constructing an acute triangle. Is your

friend correct? Explain your reasoning.

Determine whether you can construct many one or no triangle(s)

with the given description. Explain your reasoning.

21.

a triangle with angle measures of 50 70 and 100

22.

a triangle with one angle measure of 60 and one 4-centimeter side

23.

a scalene triangle with a 3-centimeter side and a 7-centimeter side

24.

an isosceles triangle with two 4-inch sides that meet at an 80 angle

25.

an isosceles triangle with two 2-inch sides and one 5-inch side

26.

a right triangle with three congruent sides

27.

Consider the three isosceles triangles.

x

50

65

130

25

x

45

x

a.

Find the value of x for each triangle.

b.

What do you notice about the angle measures of each triangle?

c.

Write a rule about the angle measures of an isosceles triangle.

22

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