Question

Q1.Find the third angle of a triangle given that its two
angles are:
(i) 54° and 45°
(ii) 35° and 95°
(iii) 46° and 27°
​

Answer 1

Answer:

If you add all three interior angle measures together in a triangle it will always equal 180°.. To find a third angle you will subtract the sum of the two given angles from 180°. Look at the 3 examples below.

72° + 50° + 58° = 180°

103° + 47° + 30° = 180°

90° + 36° + 54° = 180°

Now let's look at what to do when we are given 2 angles but we are missing the 3rd angle.

Step 1: add the two angles that you are given together

Step 2: subtract your answer from 180

Example 1:

Step 1: 30° + 35° = 65° Step 2: 180° - 65° = 115° m B = 115°

Example 2:

Step 1: 90° + 20° = 110° Step 2: 180° - 110° = 70° m F = 70°

Example 3:

Step 1: 125° + 20° = 145° Step 2: 180° - 145° = 35° x° = 35

The key to finding the missing angle measure of a triangle is to remember that the sum of the interior angles of any triangle is always 180°. If you know 2 angles then you can subtract their sum from 180° to find the measure of the 3rd angle.

Answer 2

Answer:

(i)81°

(ii)50°

(iii)107°