Shortcut Trick
Let the smaller angle be x. The larger angle is 3x − 6°.
Since the angles are complementary, their sum is 90°.
Go through the options for the larger angle (L):
If L = 66°, then the smaller angle is 90° − 66° = 24°.
Check the condition: 3 × 24° − 6° = 72° − 6° = 66°, which perfectly matches.
∴ The correct answer is 66°.
Alternate Method
Given:
Two angles are complementary.
The larger angle is 6° less than thrice the smaller angle.
Formula Used:
Sum of complementary angles = 90°
Calculations:
Let the smaller angle be x.
Then, the larger angle = 3x − 6°
⇒ x + (3x − 6°) = 90°
⇒ 4x − 6° = 90°
⇒ 4x = 96°
⇒ x = 24°
Now, find the measure of the larger angle:
⇒ Larger angle = 3 × 24° − 6°
⇒ Larger angle = 72° − 6°
⇒ Larger angle = 66°
Let's explain why other options are incorrect:
⇒ Option (1) 54°: If the larger angle is 54°, the smaller angle is 90° − 54° = 36°. Thrice the smaller angle minus 6° is 3 × 36° − 6° = 102°, which is not equal to 54°.
⇒ Option (2) 63°: If the larger angle is 63°, the smaller angle is 90° − 63° = 27°. Thrice the smaller angle minus 6° is 3 × 27° − 6° = 75°, which is not equal to 63°.
⇒ Option (3) 57°: If the larger angle is 57°, the smaller angle is 90° − 57° = 33°. Thrice the smaller angle minus 6° is 3 × 33° − 6° = 93°, which is not equal to 57°.
∴ The correct answer is 66°.
Additional Information
Complementary Angles
Two angles are complementary if the sum of their measures is exactly 90°. If one angle is θ, its complement is 90° − θ.
Supplementary Angles
Two angles are supplementary if the sum of their measures is exactly 180°. If one angle is θ, its supplement is 180° − θ.
Conjugate Angles
Two angles are conjugate (or explementary) if their sum is exactly 360°.