Question

calcule 3cos² 30° + 3 sen² 30° - 20

Answer 1

3cos²30 + 3sen²30 - 20 =
3.(\/3/2)² + 3.(1/2)² - 20 =
3 . 3/4 + 3.1/4 - 20 = 
9/4 +3/4 - 20 = 
12/4 - 80/4 = 
-68/4 = 
-34/2 = 
-17