Quick vocab:
sin=sine
cos=cosine
tan=tangent
theta=the angle
o=opposite side from angle
h=hypotenuse of triangle
a=adjacent side to angle
Three equations:
sin(theta)= o / h
cos(theta)= a / h
tan(theta)= o / a
Explanation of problem:
sin(x)= o / h
sin(x)= 16cm / 28cm
You'll substitute the 16cm in for o and 28cm for h
This is because 16cm is on the side that's opposite from the angle
28cm is on the hypotenuse of the triangle
One way to find the hypotenuse is look where the 90° is at and it's opposite from that
since you're trying to find the angle you'll have to inverse the sin to get it on the other side of the equal sign
Inverse is doing the opposite of so the inverse of sin is sin^-1

x = sin^-1 (16cm/28cm)
Answer:
x = 34.84990458°
I don't know how far rounded you'll need it
I hope this helped!
-16x+40 is the solution of this problem.
Answer: 12 friends.
Step-by-step explanation:
the data we have is:
Mei Su had 80 coins.
She gave the coins to her friends, in such a way that every friend got a different number of coins, then we have that:
The maximum number of friends that could have coins is when:
friend 1 got 1 coin
friend 2 got 2 coins
friend 3 got 3 coins
friend N got N coins
in such a way that:
(1 + 2 + 3 + ... + N) ≥ 79
I use 79 because "she gave most of the coins", not all.
We want to find the maximum possible N.
Then let's calculate:
1 + 2 + 3 + 4 + 5 = 15
15 + 6 + 7 + 8 + 9 + 10 = 55
now we are close, lets add by one number:
55 + 11 = 66
66 + 12 = 78
now, we can not add more because we will have a number larger than 80.
Then we have N = 12
This means that the maximum number of friends is 12.
For 3 it’s b. For 2 it’s 8. For 4 it’s the whole number