1. The first graph is just the sine function shifted down two units
Here's the graph of both : https://www.desmos.com/calculator/pl7ix8zvkb
2.. This is just the cosine graph with a period 1/2 as long as the parent function and shifted up by 1 unit
Here's the graph of both: https://www.desmos.com/calculator/nokkptgkli
3. A little difficult, but here's one possibility...
In the first second the pendulum swings to the max position (to the right)
In the next second, it returns to its neutral position
In the third second, it swings to min position (to the left )
In the last second, it returns to the neutral position again
So....the function is
y = 6sin (pi * t / 2)
Here's the graph : https://www.desmos.com/calculator/0cslmqnaad