A right-angled triangle contains an angle of 65°. What is the size of the third angle?
In a right-angled triangle, the sum of all angles is always 180°. Since one angle is 90°, the sum of the other two angles must be 180° - 90° = 90°.
Therefore, the sum of the other two angles is 90°, and one angle is given as 65°, so the third angle must be 90° - 65° = 25°.
The size of the third angle is 25°.
To find the size of the third angle in a right-angled triangle, we can use the fact that the sum of the angles in any triangle is 180°.
In a right-angled triangle, one of the angles is always 90° (the right angle).
Therefore, we can find the size of the third angle as follows:
Step 1: Subtract the sum of the two known angles (90° and 65°) from 180°:
180° - 90° - 65° = 25°
Step 2: The third angle in the right-angled triangle has a size of 25°.