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### Course: MAP Recommended Practice > Unit 8

Lesson 4: Missing angle problems- Find measure of vertical angles
- Finding missing angles
- Find measure of angles word problem
- Equation practice with complementary angles
- Equation practice with supplementary angles
- Equation practice with vertical angles
- Create equations to solve for missing angles
- Unknown angle problems (with algebra)

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# Find measure of vertical angles

Given two intersecting lines and the measure of vertical angles, watch as we solve to find the measure of the remaining angles. Created by Sal Khan.

## Want to join the conversation?

- I still don't fully understand this is there another video to help me?(44 votes)
- For some reason, whatever the number is on the other side is your answer(11 votes)

- you may never use them. But it's good to learn them, just in case an everyday problem comes up that involves angles. You'll be able to solve it and help everyone else out because you saw that video on Khan Academy in 7th grade. :)(16 votes)
- Who would remember this(7 votes)

- I have no idea how to do this. I feel so stupid. How do I find the value of the angles? Every time I type out an answer, it ends up being an answer that was right in front of me the whole time. Can someone help me?(9 votes)
- I think you have probably figured it out by now, but here's what's worked for me.

Figure out if the angle is:

complementary (adds up to 90 degrees) or

supplementary (adds up to 180 degrees)

Then take the given value and subtract it from 180 or 90, depending on the type of angle.

examples:

X=47, complementary angle

90 - 47 = 43

the angle is 43 degrees

Y=125, supplementary angle

180 - 125 = 55

the angle is 55 degrees

Hope this helps!(1 vote)

- guys it makes sense wdym(4 votes)
- I'm so confused. How do we fine the remaining angles?(4 votes)
- do u guys get in because I am confuzzled(4 votes)
- The two angles in between the yellow lines are the same which means that each angle has to have the same value. Soooo if you can find a (the smallest) number for x that makes both side the same number... YOU WIN MATH

BTW The x right next to the 7 means there is an inviscible times simbul if you were wondering

You don't always have to use the technique that they use! What works for you works for you. Hope this helps :)(1 vote)

- I'm confused someone explain it all to me(3 votes)
- So Basically, 60 degrees + x = 7x, so if you subtract the x on both sides , you get 60 = 6x, because x = 1x ! The whole area is 70 degrees, and 7x is 70 divided by 7, which is 10 ! So x is 10 !(2 votes)

- i sill dont understand this or how to do it? so what do i do(3 votes)
- my work is saying onward to where i could not do it.(3 votes)
- For some reason i don't know how to do it can you explain me to this like im a 2 year old?(3 votes)
- All you have to remember is that the opposite part is equals to each other(0 votes)

## Video transcript

So we have two
intersecting lines here, and then we have this
other purple-looking line. And then they've
given us some angles. They tell us that the measure
of this angle right over here is 7x. The measure of this angle
right over here is 60 degrees. And the measure of this
angle right over here is x. So let's try to figure out
what all of these angles are. So to do that, we have
to figure out what x is. And there's a big clue here,
because the 60-degree angle plus the x angle,
they're adjacent. And if you add these two angles
together, their outer rays, our vertical angle
with this 7x angle. So we could say-- and just to
visualize that a little better, let me color it in. Actually, let me do it this way. You see that this
angle out here-- let me do it in a color
I haven't used yet. This entire angle
over here, which is going to be 60
degrees plus x, that's a vertical angle with
this angle, the one that has measure 7x. So we could say that 60
degrees plus x is equal to 7x because vertical
angles are equal. So let's write that down. We get 60. And we'll assume that
everything is in degrees. 60 plus-- let me do that
in this other color. 60 plus x is going
to be equal to 7x. And now we just
have to solve for x. So the simplest
thing to do would be to get all over x's on
one side of the equation. I've already gotten seven
x's on this right-hand side, so let's get rid of all of
the x's on the left-hand side. And the easiest way
to get rid of this x is to subtract x from
the left-hand side. But of course, in order
to keep it an equation, we can't just do
something to one side. Otherwise, it won't
be equal anymore. We have to do it to both sides. So let's subtract
x from both sides. And on the left-hand side,
we are left with just the 60. So we're left with just a 60. And then that is going to
be equal to 7x minus x. If I have 7 of something
and I get rid of 1 of them, I'm going to have 6 of
that something left. So that's going
to be equal to 6x. So we have 6 times
something is equal to 60. You could probably figure
that out in your head. But I will do it a
little systematically. We can divide both sides
by 6 to solve for x. So let's do that. And we would be left
with x is equal to. 60 divided by 6 is 10. And we reminded ourselves that
everything was in degrees. And we could even do that here. This was in degrees. This is in degrees. And so this is in
degrees right over here. So the measure of this angle
right over here is 10 degrees. So this one right over
there is 10 degrees. This is, of course, 60 degrees. You add them together, 60
degrees plus 10 degrees is 70 degrees. So this bigger angle right
over here is 70 degrees. And of course, this one over
here, it's a vertical angle. It's going to have
to be the same. And we see that, 7 times x. 7 times 10 degrees is
70 degrees as well.