Step-by-step explanation:
We know that tan=sin/cos, so tan(x+π/2)=

Then, we know that sin(u+v)=sin(u)cos(v)+cos(u)sin(v),
so our equation is then
Then, cos(u+v)=cos(u)cos(v)-sin(u)sin(v), so our expression is then

there are links so I could not put them in directly but hope my sticker not helps I tried my best
<span>The number of ways to permute three correct answers among five questions is 5Choose3 which is 5!/(3!*2!) which equals 10.
We must then have the correct answer three times which happens .25 of the time, and two wrong answers 75 of the time.
So the probability is 10*0.25^3*.75^2 which is 0.087890625 or roughly an 8.8% chance.</span>
It is. 7.17285714285714 you can stop at the thousands