1)
LHS = cot(a/2) - tan(a/2)
= (1 - tan^2(a/2))/tan(a/2)
= (2-sec^2(a/2))/tan(a/2)
= 2cot(a/2) - cosec(a/2)sec(a/2)
= 2(1+cos(a))/sin(a) - 1/(cos(a/2)sin(a/2))
= 2 (1+cos(a))/sin(a) - 2/sin(a)) (product to sums)
= 2[(1+cos(a) -1)/sin(a)]
=2cot a
= RHS
2.
LHS = cot(b/2) + tan(b/2)
= [1 + tan^2(b/2)]/tan(b/2)
= sec^2(b/2)/tan(b/2)
= 1/sin(b/2)cos(b/2)
using product to sums
= 2/sin(b)
= 2cosec(b)
= RHS
First step, divide 6 from both sides.
t/6=r^2+1
second step, subtract 1 from both sides
t/6 -1=r^2
Now take the square root of each side.

Done!
Answer:
y = 9
Step-by-step explanation:
So if x = 3, we can sub that into the equation.
This gives us:
6.4 (* 3) + 2.8y = 44.4
so:
19.2 + 2.8y = 44.4
25.2 = 2.8y
so
y = 9
The question is "What's Stella's opportunity cost of working on her serve for an hour?" The rest of the info looks like it's meant to confuse you. They charge $10 an hour. She values an hour of her time at $20. I believe that means she would pay $20. Hope this helps!