## Angles in the roof (1)

GCSE Text:
The design of the roof beams in a new building is shown in this diagram: Using your knowledge of angle rules:

a) Calculate the size of angle a

b) Calculate the size of angle b

c) Calculate the size of angle c

Suggestions:
This video was made when a school building was being constructed on site. KIER Construction kindly allowed a number of videos to be made so that students could grasp the use of Maths in the construction industry. Students very much enjoy seeing a professional (other than a teacher) talk about design, specification and mathematics, and it is a firm favourite. It takes many students over 5 minutes to spot the important elements of the design, and as such is a valuable class resource.

Extension Ideas:
Teachers could extend the learning by considering:

• Adding extra angles to find – a ‘d’ placed in the ‘V’ directly beneath angle b in the diagram stretches many students, although you will need to add arrows on the inner lines to show that they are parallel.
• Recreate the roof design as a ‘lean to’ so the line between angles a and b extends upwards over the ‘diagram not accurately drawn’ label, and then comes down to make a right angle triangle at the vertex where the 17º angle is. There are a number of angles that can be calculated if this is done.