Working out angles III

Working out angles III

Auto-markingPencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about working out angles from known properties of interior angles of shapes.

Question 1Change answer

a)  Work out the size of angles x and y for the diagram above.
x =  degrees          y =  degrees

Question 1Change answer

b)  Work out the size of angles x and y for the diagram above.
x =  degrees           y =  degrees

Question 1Change answer

c)  Work out the size of angles x and y for the diagram above.
x =  degrees           y =  degrees

Question 1Change answer

d)  Work out the size of angles x and y for the diagram above.
x =  degrees           y =  degrees
Task administration: 
This task can be completed with pencil and paper or online (with auto marking displayed to students).
Level:
5
Curriculum info: 
Maths, Geometry and Measurement, Shape
Keywords: 
angles, interior angles, circles, diameter, triangles
Description of task: 
Students use the angle-in-a-semicircle property, and the sum of the angles in a triangle to find unknown angles.
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Geometric thinking, set 6
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
 

Y10 (10/1998)
a) i)
ii)		 90
65		 difficult
difficult
b) i)
ii)		 55
55		 difficult
difficult
c) i)
ii)		 100
30		 very difficult
very difficult
d) i)
ii)		 50
80		 very difficult
very difficult
Diagnostic and formative information: 
  Common error Likely calculation Likely reason
a) i)
    ii)		 77.5
77.5		 (180 - 25) ÷ 2
(180 - 25) ÷ 2		 Sees triangles as isosceles.
c) i)
    ii)
d) i)
    ii)		 95 approx.
40 approx.
55 approx.
70 approx.		   Measures angles with a protractor.

(May indicate a) and b) are measured by a protractor too).