Question

What is the measure of the missing angle?




A.


60°


B.
20°


C.


50°


D.


40°

Answer 1

@mathmale

Answer 2

Some comments:

The triangle illustrated is "isosceles," meaning that two of its sides are of equal length, BECAUSE two of its angles are equal.

Recall what we did in the previous problem: Apply the fact that the sum of the interior angles of a triangle is always 180 degrees. So, what are you going to do next?

Answer 3

A?

Answer 4

@mathmale

Answer 5

I'd much prefer that you show me how you obtained what you think is the correct answer. What did you do here?

Answer 6

i'm not really sure @undeadknight26

Answer 7

This is your opportunity to learn how to do these problems yourself. I believe I've told you before that the sum of all the interior angles of a triangle is always 180 degrees.

What is the sum of 70 degrees and 70 degrees?

What would you do next towards finding the answer to this question?

Answer 8

I have to say it's disappointing for me that you ask another person for help instead of using the clues I've given you to help you solve this problem yourself.

Answer 9

well,... thanks for your help never mind

Answer 10

not everyone can get it fast. Im kind of slow at this sometimes

Answer 11

Is that a good reason for abandoning our conversation and asking someone else for help?

Answer 12

well i didnt think you wanted to help me because i didnt get so fast

Answer 13

Let the unknown angle be x. The other two angles are 70 and 70 degrees.

Write an algebraic expression for the sum of these three angles.

Answer 14

Example: the "sum" of a, b and c is a+b+c.

Answer 15

oh 50

Answer 16

so its 50

Answer 17

First, please add 70 to 70.

Answer 18

70+70= 140

Answer 19

Good. Remember, the sum of the measures of the 3 interior angles inside that triangle is 180 degrees. So, please subtract 140 degrees from 180 degrees.

Answer 20

140-180= -40

Answer 21

so its 40

Answer 22

Subtract 140 degrees FROM 180 means that 180 comes first, 140 second. Yes, the difference is 40 degrees, and so that is the answer you wanted.

Answer 23

thank you so much for being patient with me :)

Answer 24

Review: the sum of the measures of the interior angles of a triangle is always 180 degrees.

Here, that sum is 70 + 70 + x = 180

or 140 + x = 180

Subtracting 140 from both sides will give you x=40 degrees.