I really need help on this question, it is math and i am clueless, could someone help me please?

Question

The equation x² + y² = 1 can be rewritten using x = cos(t) and y = sin(t). The x and y can be squared and substituted, giving cos²(t) + sin²(t) = 1.

1.     Use the equations above to determine two values of cos(t) when sin(t) = 0.5852.

2.     Use the equations above to determine two values of sin(t) when cos(t) = -0.7429.

Answer 1

1. cost = 0.8109 or - 0.8109 = 2 values of x in the original equation
2. sint = 0.6694 or -0.6694 = 2 values of y in the original equation

the equation is a circle. For any x value there are 2 y values, for any y value there are 2 x values, but x and y are each between 1 and -1 in value.

you can use a calculator with the inverse trig function to find the angle, then find the trig value

or square 0.5852 and subtract from 1 to get .6575 then take the square root, to get + or - 0.8109 = x=cost

and square 0.7429 and subtract from 1, then take the square root to get + or - 0.6694 =y=sint