1. Starter Questions www.mathsrevision.com B 6 co A C 8 34o General
Sunday, 09 December 2018
Created by Mr Lafferty

2. To identify isosceles triangles
Isosceles triangles in Circles
General
Aim of Today’s Lesson
To identify isosceles triangles
within a circle.
Sunday, 09 December 2018
Created by Mr Lafferty

3. Isosceles triangles in Circles
General
When a line is drawn between two points on a circle
it is called a CHORD.
If the line passes through the
Centre it is called a diameter. A B xo xo
When two radii are drawn
to the ends of a chord, an
isosceles triangle is formed. C
Sunday, 09 December 2018
Created by Mr Lafferty

4. Isosceles triangles in Circles
General
Special Properties of Isosceles Triangles
Two equal lengths
Two equal angles
Angles in any triangle sum to 180o
Sunday, 09 December 2018
Created by Mr Lafferty

5. Isosceles triangles in Circles
General
Q. Find the angle xo.
Solution
Angle at C is equal to: B xo C
Since the triangle is isosceles
we have A
280o
Sunday, 09 December 2018
Created by Mr Lafferty

6. Begin Maths in Action Worksheet 1
Isosceles triangles in Circles
General
Begin Maths in Action Worksheet 1
Sunday, 09 December 2018
Created by Mr Lafferty

7. Starter Questions www.mathsrevision.com B bo 5 A C 12 27o General
Sunday, 09 December 2018
Created by Mr Lafferty

8. To find the special angle
Angles in a Semi-Circle
General
Aim of Today’s Lesson
To find the special angle
in a semi-circle
Sunday, 09 December 2018
Created by Mr Lafferty

9. Isosceles triangles in Circles
General
On your worksheet, mark the point P on the
circumference of the semicircle.
Joint the points AP and BP together.
Measure angle ∠APB P A B
The angle in a semi-circle is ALWAYS 90o
Sunday, 09 December 2018
Created by Mr Lafferty

10. Angles in a Semi-Circle
General
KeyPoint for Angles in a Semi-circle P A B
A triangle APB inscribed within a semicircle
with hypotenuse equal to the diameter
will ALWAYS be right angled at P on the circumference.
Remember - Angles in any triangle sum to 180o
Sunday, 09 December 2018
Created by Mr Lafferty

11. Finish Maths in Action Worksheet 2
Angles in a Semi-Circle
General
Finish Maths in Action Worksheet 2
Then Page 114
Ex3 Q3,Q4,Q5
Sunday, 09 December 2018
Created by Mr Lafferty

12. Starter Questions www.mathsrevision.com x xo 4 z y 3 56o General
Sunday, 09 December 2018
Created by Mr Lafferty

13. Solve harder semi-circle problems
Angles in a Semi-Circle
General
Aim of Today’s Lesson
Solve harder semi-circle problems
Sunday, 09 December 2018
Created by Mr Lafferty

14. Angles in a Semi-Circle
General
Example 1 : Sketch diagram and find all
the missing angles.
20o
Hints
43o
Look for right angle triangles
Remember !
Angles in any triangle
sum to 180o
47o
70o
Sunday, 09 December 2018
Created by Mr Lafferty

15. Angles in a Semi-Circle
General
Example 2 : Sketch the diagram.
(a) Right down two right angle triangles
(a) Calculate all missing angles. D C
60o E
25o A B
Sunday, 09 December 2018
Created by Mr Lafferty

16. Angles in a Semi-Circle
General
Page 114 Ex4 Q1 – Q3
Then Worksheet 3
Sunday, 09 December 2018
Created by Mr Lafferty

17. Starter Questions www.mathsrevision.com General
Sunday, 09 December 2018
Created by Mr Lafferty

18. Angles in a Semi-Circle
General
Pythagoras Theorem
Aim of Today’s Lesson
How we can use Pythagoras Theorem
to calculate length within a circle
Sunday, 09 December 2018
Created by Mr Lafferty

19. Angles in a Semi-Circle
General
Pythagoras Theorem
We have been interested in right angled triangles within
a semi-circle. Since they are right angled we can use
Pythagoras Theorem to calculate lengths.
Example 1 : Calculate the value of d P A B
4cm
3cm
d cm
Sunday, 09 December 2018
Created by Mr Lafferty

20. Angles in a Semi-Circle
General
Pythagoras Theorem
Example 2 : Calculate the length of XY Y
12cm cm X Z
13 cm
Sunday, 09 December 2018
Created by Mr Lafferty

21. MIA Page 116 Ex5 Angles in a Semi-Circle www.mathsrevision.com
General
Pythagoras Theorem
MIA Page 116 Ex5
Sunday, 09 December 2018
Created by Mr Lafferty