Answer:
cosA = √(21/25)
Step-by-step explanation:
We know
sin²(A) + cos²(A) = 1
Next, we know that sin(A) = 2/5. Plugging that into our equation, we get
(2/5)² + cos²A = 1
4/25 + cos²A = 1
subtract 4/25 from both sides to isolate cos²A
cos²A = 1 - 4/25 = 25/25-4/25 = 21/25
square root both sides to get
cosA = √(21/25)
We do not include -√(21/25) in our possible answer for cosA because this is in quadrant 1, so cosA must be positive.
The wrong statement: The volume or the smaller cone cannot be determined because its height is unknown.
We already know that the larger cone has a height of 8 cm and that the smaller cone is just 1/4 of 8 cm.
8×1/4 = 2 cm.
You can still find its volume by using the formula 1/3πr^2.
