Question

You know that sin(x) + cos(x) is 1.2. What is the sin(x)cos(x)?

Answer 1

Write s = sin x and c = cos x

Then s + c = 1.2

Now square both sides

1.44 = s^2 + 2sc + c^2.

You can now solve for sc.

Answer 2

Your method is perfectly correct.

Answer 3

relieved?

Answer 4

At what?

Answer 5

Very. I was worried I might have used a less than perfectly correct method.