Thursday 3_4

Inequalities and triangles

Thursday 3/4 Starter

Inequalities

 $<\ \ \le\ \ \ge\ \ >$  

• smaller number < greater number

• Greater number > smaller number 

• FOR EXAMPLE:

• 4 < 9 and 9 > 4

Fill in the Blank

 $9\ <\ or\ >\ -22$  

Type in 
< 
or
 > 

Fill in the Blank

 $7\ <or>\ 15$  

Type in either < or >

Fill in the Blank

 $19\ +\ 6\ <\ or\ >\ 13$  

Fill in the Blank

 $-10\ +\ 7\ <\ or\ >\ -1$  

Interior Angles of Triangles

• Must add up to  $180\degree$  

• Example: 45 + 45 + 90 = 180 so the angles DO MAKE A TRIANGLE

• Non-example: 30 + 50 + 90 = 170 so the angles DO NOT MAKE A TRIANGLE

Multiple Choice

Do these angles add to make a triangle?

 $36\degree+90\degree+80\degree$  

• Yes

• No

• Sometimes

Multiple Choice

Do these angles make a triangle?

 $135\degree+21\degree+24\degree$  

• Yes

• No

• Almost

Finding missing angles

• Double check what the question is asking!

• If you are given two angles you can find the third:

• 63 + 100 + x = 180

• 163 + x = 180 (subtract 163)

• x = 17

Fill in the Blank

What is the missing angle?

Solve for x

• Start the same way -- add all angles up to 180

Solve for x

Find the missing angle

180 - 124 - 40 = 16

Set equal to third angle

4x = 16 (divide by 4)

x = 4

Fill in the Blank

Solve for x