The triangle below has two angles of size 70°, as shown (diagram not to scale) - Junior Cycle Mathematics - Question 7 - 2022
Question 7
The triangle below has two angles of size 70°, as shown (diagram not to scale).
(i) What type of triangle is this? Tick (✓) one box only.
Right-angled ☐
Isoscele... show full transcript
Worked Solution & Example Answer:The triangle below has two angles of size 70°, as shown (diagram not to scale) - Junior Cycle Mathematics - Question 7 - 2022
Step 1
What type of triangle is this?
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Answer
This triangle is isosceles, as it has two equal angles of 70°.
Step 2
Work out the size of the angle A, the third angle in this triangle.
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Answer
To find the size of angle A, we use the fact that the sum of angles in a triangle is 180°.
Therefore,
180°−(70°+70°)=40°
Thus, angle A is 40°.
Step 3
Work out the size of the angle B.
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Answer
In the triangle joined to the parallelogram, we know that opposite angles in a parallelogram are equal. Since one angle is 70°, angle B must also be 110°, calculated as follows:
B=180°−70°=110°.
Step 4
Is this triangle definitely congruent to T?
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