We have the formula (sin x)^2 + (cos x)^2 = 1;
Then, sin α =

cos β =

We apply the formula sin ( α + β ) = sin α x cos β + sin β x cos α = (3/5)x(4/5) + (4/5)x(3/5) = 12/25 + 12/25 = 24/25;
Answer:
43
Step-by-step explanation:
I would see a pattern like this
1 4 6 2 5 7 8 9 7 15 41 ?
------------------- ---------
start pattern key
then
15 = 8 × 2 - 1
a10 = a7 × a4 - a1
41 = 9 × 5 - 4
a11 = a8 × a5 - a2
? = 7 × 7 - 6 = 43
a12 = a9 × a6 - a3