How do you find exact values?

Using trigonometric identities: A trigonometric identity is a relationship between trigonometric functions that we can use to find an exact value of a trigonmetric function.Using the unit circle: The unit circle is a circle with its center at the origin and a radius of 1 unit. If we place an angle, θ, with its initial side along the positive x-axis, then the point where the angle's terminal side intersects the unit circle is (cos(θ), sin(θ)).Using reference angles: Reference angles are the smallest angle that the terminal side of an angle makes with the x-axis. As it turns out, trigonometric functions of an angle and its reference angle have the same value, except that they may have different signs.

For example, suppose we want to find the exact value of tan(405°). First, we take a look at the angle 405° on a graph with the unit circle:

in this that the reference angle of 405° is 45°. We can use the fact that tangent is positive in the first quadrant and the rule for reference angles to deduce that tan(405°) = tan(45°). Then we can use the well-known fact that tan(45°) = 1 to get that tan(405°) = 1.

Step-by-step explanation:

4.5%

step-by-step explanation:

hello!

to begin with, we're given that on earth, a rock weighs 20 pounds, and while on jupiter, that same rock weighs 42 pounds. now, we're trying to find the weight of a rock that weighs 10.5 pounds on earth, on jupiter.

to solve this, first, set up a proportion, cross-multiply, and solve it algebraically.

setting up the proportion is the hardest and the most confusing part of the problem, but it's simple.

if on earth, the rock weighs 20 lbs, and on jupiter it weighs 42 lbs, our first part of our proportion is 20/42 lbs. the second part has to be equal to each other. this means that 10.5 has to be on the numerator of the fraction, and x, the value we're trying to find, has to be on the denominator. remember that the rock weighs 10.5 lbs on earth, and we're trying to find the weight of it on jupiter (which is x).

20/42 = 10.5/x

next, you would cross-multiply.

20x = 42(10.5)

20x = 441

now, solve it algebraically by using division.

x = 22.05 lbs

this can be rounded to 22.1 lbs.

therefore, the weight of the rock on jupiter is 22.1 lbs, the fourth choice.