ron and amber bought a pizza. ron ate 3/10 of the pizza. amber ate 1/10 of the pizza. together,which fraction of the pizza did they eat?

4/10 or 2/5

Step-by-step explanation:

it's simple, we add the fractions 3/10 and 1/10

since the denominators are the same we only add the top parts and leave the bottom alone.

so 3 + 1 = 4

    10  10  10

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.