Question

What is the measure of angle D?

Answer 1

The SUM of the three angles of a triangle equals 180 degrees. So write an equation that represents what was just said.

Answer 2

and the measure of e also.

Answer 3

Just write an equation that represents the concept "the sum of the 3 angles of a triangle is 180 degrees."

Answer 4

Can you write the equation?

Answer 5

(2x+5)+(2x+10)+(x-5)=180

Answer 6

thats not right is it?

Answer 7

exactly. Now solve for x.

Answer 8

would i combine like terms?

Answer 9

The first one should read 2x+25, not 2x+5..you made a typo

Answer 10

sorry. thanks for correcting me

Answer 11

Yes, combine like terms on the left side... combine all the x's and combine the numbers...what do you get?

Answer 12

x=38

Answer 13

How did you get that? What did you get on the left side after you combined like terms?

Answer 14

Did you get 5x + 30?

Answer 15

crap. sorry i put five on my paper too! yes i got thrity the second time.

Answer 16

x=30

Answer 17

so you have 5x + 30 = 180

Subtract 30 from both sides, you get 5x = 150

Divide both sides by 5, you get x = 30.

So you want angle D...angle D = 2x+ 10

How much is 2x+10 when x = 30?

Answer 18

70. thanks so much(:

Answer 19

You also wanted angle E...what will be the measure of angle E?

Answer 20

85

Answer 21

Correct. You're very welcome.

Answer 22

could i ask one more question. please(:

Answer 23

sure

Answer 24

What is the measure of angle x?

Answer 25

would it be 60

Answer 26

The 130-degree angle is called an extrior angle of a triangle.

An exterior angle of a triangle is equal to the sum of the 2 interior angles (that are not next to that exterior angle).

So 130 = 60 + x

(the 60-degree angle and the angle called x are interior angles and they are not adjacent/next to that exterior angle called 130 degrees).

Makes sense?

Now solve for x.

Answer 27

its 70 thanks!!

Answer 28

yes...

Also...there's another way to get the answer...look at the diagram....the angle right next to the 130-degree angle has measure of 50 degrees becuase they make up a straight line (they are supplementary angles).

So the e inside angles are 50, 60, and x.

so 50 + 60 + x = 180
110 + x = 180
x = 70

Thats another way to solve it.

But the first way, is important in geometry.

Answer 29

okay! thanks!

Answer 30

welcome.