Question

Evaluate 7 sin square 30 degree + 3 cos square 60 degree minus cos square 45 degree divided by sin square 70 degree + sin square 20 degree + cos

Answer 1

Answer:

2

Step-by-step explanation:

Evaluate 7 sin square 30 degree + 3 cos square 60 degree minus cos square 45 degree divided by sin square 70 degree + sin square 20 degree

(7Sin²30° + 3Cos²60°  - Cos²45°)/(Sin²70° + Sin²20°)

Using Sin30° = Cos60°   & Sin20° = Cos70°

= (7Sin²30° + 3Sin²30°  - Cos²45°)/(Sin²70° + Cos²70°)

Using Sin²70° + Cos²70° = 1

= 10Sin²30° - Cos²45°

Sin30° = 1/2

Cos45° = 1/√2

= 10 × (1/2)² - (1/√2)²

= 5/2 - 1/2

= 4/2

= 2

(7Sin²30° + 3Cos²60°  - Cos²45°)/(Sin²70° + Sin²20°) = 2