Unit 15 Section 1 : Angle Facts

In this section we revise some basic work with angles. You should already know the three rules below:
 Angles around a point add up to 360° Angles on a straight line add up to 180° Angles in a triangle add up to 180°
We can use these rules to answer geometry questions.

Practice Questions

Work out the answer to each of these questions then click on the button marked to see whether you are correct.

(a) Determine the size of angle a in this diagram:

(b) Work out the size of angle d in this diagram:

(c) Calculate the size of angle n in this diagram:

Exercises

Work out the answers to the questions below and fill in the boxes. Click on the button to find out whether you have answered correctly. If you are right then will appear and you should move on to the next question. If appears then your answer is wrong. Click on to clear your original answer and have another go. If you can't work out the right answer then click on to see the answer.

Question 1
Calculate the sizes of the angles marked by letters in the following diagrams:
 a = ° b = ° c = ° d = °
Question 2
Calculate the sizes of the unknown angles in the following triangles:
 (a) ° (b) ° (c) ° (d) °
Question 3
Calculate the sizes of the angles marked by the letter x in the following diagrams:
 (a) x = ° (b) x = ° (c) x = ° (d) x = °
Question 4
The diagram shows an isosceles triangle. What are the sizes of the two angles marked a and b?
 a = ° b = °
Question 5
Calculate the sizes of the angles marked a and b in the diagram.
 a = ° b = °
Question 6
The diagram below shows two intersecting straight lines. Calculate the sizes of the angles marked a, b and c in the diagram.
 a = ° b = ° c = °
Question 7
The diagram below shows a rectangle and its diagonals. Calculate the sizes of the angles marked a, b and c.
 a = ° b = ° c = °
Question 8
Determine the sizes of the angles marked a, b and c in the diagram shown.
 a = ° b = ° c = °
Question 9
PQR is a straight line. Determine the sizes of the angles marked a, b and c in the triangles shown.
 a = ° b = ° c = °
Question 10
Calculate the sizes of the angles marked a, b, c, d and e in the triangles shown.
 a = ° b = ° c = ° d = ° e = °

You have now completed Unit 15 Section 1
 Your overall score for this section is Correct Answers You answered questions correctly out of the questions in this section. Incorrect Answers There were questions where you used the Tell Me button. There were questions with wrong answers. There were questions you didn't attempt.
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