9. Find the size of angles X, Y and Zin the diagram.
70° 70° Z
Y 60° 60° 65° X 65°
BERMUDA TRIANGLE
10. A diagram of the Bermuda Triangle is shown. Using an appropriate scale, draw a scale diagram of the Bermuda Triangle.
BERMUDA
1 571 km
PUERTO RICO
11. Opposite is a diagram used as part of the proof for the theorem that states that the angles in any triangle sum to 180°.
Why does |∠ACB| = |∠CAE|?
15·3 Constructing triangles using angles and sides
An included angle is the angle between two given sides.
In this triangle, ∠A is the included angle between sides b and c.
A c
Construct a triangle given two sides and the angle in between them (SAS)
1
Draw a rough sketch of the triangle to be constructed. Include the given information in your sketch.
A 3 C 2
‘Side, angle, side’ is often shown using the letters ‘SAS’.
11
Draw a line segment [AB] , which has a length equal to the longest length given.
A B X
With the centre of your protractor on the point A and in line with [ AB ], measure the required angle. Mark the point X as shown. Draw a ray from A through X .
A 238 Linking Thinking 1 B B b D N B C A P M E
By the end of this section you should:
● understand what an included side and included angle are
● be able to construct a triangle given two sides and an included side
● be able to construct a triangle given two angles and a side
● be able to identify and fi nd the measure of interior and exterior angles in a triangle