Angles in a triangle

Difficulty Starter · Set 6042hd

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1
Two angles of a triangle are 40° and 20°. What is the third, in degrees?
2
Two angles of a triangle are 40° and 20°. What is the third, in degrees?
3
Two angles of a triangle are 30° and 50°. What is the third, in degrees?
4
Two angles of a triangle are 50° and 40°. What is the third, in degrees?
5
Two angles of a triangle are 50° and 40°. What is the third, in degrees?
6
Two angles of a triangle are 30° and 40°. What is the third, in degrees?
7
Two angles of a triangle are 30° and 60°. What is the third, in degrees?
8
Two angles of a triangle are 30° and 60°. What is the third, in degrees?
9
Two angles of a triangle are 40° and 40°. What is the third, in degrees?
10
Two angles of a triangle are 50° and 30°. What is the third, in degrees?
11
Two angles of a triangle are 40° and 50°. What is the third, in degrees?
12
Two angles of a triangle are 20° and 40°. What is the third, in degrees?
13
Two angles of a triangle are 30° and 60°. What is the third, in degrees?
14
Two angles of a triangle are 50° and 40°. What is the third, in degrees?
15
Two angles of a triangle are 30° and 60°. What is the third, in degrees?
16
Two angles of a triangle are 50° and 40°. What is the third, in degrees?
17
Two angles of a triangle are 50° and 30°. What is the third, in degrees?
18
Two angles of a triangle are 50° and 50°. What is the third, in degrees?
19
Two angles of a triangle are 20° and 20°. What is the third, in degrees?
20
Two angles of a triangle are 40° and 40°. What is the third, in degrees?

What is in this set

The numbers in this set run from 20 to 70.
A careful solution takes 2 written steps on average.
The mistake this set invites most often, in 100% of the problems: the angles of a triangle add to 180°, not 360°.
Answers are a whole number.

Drawing 240 problems from this page produced 22 different ones, 9% — so a sheet of 20 will come back to a problem you have seen — there are only so many sensible ones of this kind.

The same skill, harder or easier

We would put this in front of a grade 6 class. That is our judgement, not a standard, and it is printed here so you can disagree with it. Everything else we put in that year.