IGCSE Circle Theorems Revision

​Before we start to revise circle theorems, let's review what we know about angles.

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​Please write down anything in this picture you were not confident on!

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​You can come back to this slide as well.

Remember : the sum of the exterior angles for any polygons is always 360 degrees!

Add up all the angles:

90 + 60 + 46 + 73 = 269

Subtract from 360:

360 - 269 = 91

answer:

x = 91

​If at this point you would like to do some more practice on these type of questions (Angles in Parallel lines, polygons and exterior/interior angles)

​That is absolutely fine!

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Please head now to Dr Frost where there are questions and videos to help you.

The angle in a semi-circle is a right angle.

The angle at the circumference is double the angle at the centre.

The angle between a tangent and a chord is equal to the angle in the alternate segment.

Angles in the same segment are equal

The perpendicular from the centre to a chord bisects the chord.

Two tangents from a point to a circle are equal.

The tangent to a circle is perpendicular to the radius at the point of contact.

Let's see what you've learned...

​See link on classroom

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​https://corbettmaths.com/wp-content/uploads/2013/02/circle-theorems.pdf