geometry-reasoning-angles-within-circles

# Interactive video lesson plan for: Geometry Reasoning: Angles within Circles

#### Activity overview:

Geometry Teachers Never Spend Time Trying to Find Materials for Your Lessons Again!

http://geometrycoach.com/Geometry-Lesson-Plans/?pa=MOOMOOMATH
Geometry Reasoning: Angles inside and outside Circles

In this video you will learn how to find the angle measure of angles created inside, and outside circles.
The first problem involves finding an angle using a big ac and the small arc.
The second problem involves using vertical angles.
Finally, the last problem involves linear pairs of angles.

Transcript:
Number 8 We have an angle that is in the circle but it is not in the center and it is not inscribed, so we have to look at the intercepted arcs, add them, and divide by two.
Take 160 + 50 and divide by 2.
This equals 210 and divide by 2 which equals 105.
Therefore angle 8 is 105 and the vertical angle is also 105.
Let's now look at number 9
We have an angle on the outside.
The rule for this one is?
We have a big arc, a small arc, and an exterior angle.
The rule is big arc, minus small arc divided by two equals the angle
I'm going to call this arc we are looking for x
Therefore I will get x-47/2 = 30/1.
Solve by taking a cross product and you get 60 equals x -47
Next, add 47 to both sides and this equals 107.
That means the arc is 107 degrees.
Remember, the big arc minus the small arc equals the angle on the outside of the circle.
Number 10 We have an angle right here, and what kind of angle are we looking for?
Here i the vertex, and the vertex lies on the circle
It is on a tangent line, but notice the vertex is right on the circle.
If this angle is 156 then what do we know about the linear pair?
Linear pairs add to 180 degrees.
I will take 180 minus 156 and that equals 24 degrees.
So 24 is the answer to the problem with the linear pair.

You may also enjoy...

NCEA Maths Level 1 Geometric Reasoning: Angles Within Circles

About MooMooMath: We provide helpful Math and Geometry videos to help you solve Math problems, or review old Math concepts you may need to refresh. If you’re a Math student or teacher, we'd love to have you subscribe and join us! We upload a new video every day
* Subscribe
http://bit.ly/1d8EvIu

Let’s connect
MooMooMath
http://www.moomoomath.com/
* Pinterest
https://www.pinterest.com/moomoomath/

-~-~~-~~~-~~-~-
Please watch: "Study Skills Teacher's Secret Guide to your Best Grades"
-~-~~-~~~-~~-~-

Tagged under: circles,angles,inscribed,circle arcs,vertical angles,linear pair,geometry,tangent,geometry reasoning

Clip makes it super easy to turn any public video into a formative assessment activity in your classroom.

Add multiple choice quizzes, questions and browse hundreds of approved, video lesson ideas for Clip

Make YouTube one of your teaching aids - Works perfectly with lesson micro-teaching plans

Play this activity

1. Students enter a simple code

2. You play the video

3. The students comment

4. You review and reflect

* Whiteboard required for teacher-paced activities

## Ready to see what elsecan do?

With four apps, each designed around existing classroom activities, Spiral gives you the power to do formative assessment with anything you teach.

Quickfire

Carry out a quickfire formative assessment to see what the whole class is thinking

Discuss

Create interactive presentations to spark creativity in class

Team Up

Student teams can create and share collaborative presentations from linked devices

Clip

Turn any public video into a live chat with questions and quizzes

### Spiral Reviews by Teachers and Digital Learning Coaches

@kklaster

Tried out the canvas response option on @SpiralEducation & it's so awesome! Add text or drawings AND annotate an image! #R10tech

Using @SpiralEducation in class for math review. Student approved! Thumbs up! Thanks.

@ordmiss

Absolutely amazing collaboration from year 10 today. 100% engagement and constant smiles from all #lovetsla #spiral

@strykerstennis

Students show better Interpersonal Writing skills than Speaking via @SpiralEducation Great #data #langchat folks!