First we will convert those radian angles to degrees, since my mind works better with degrees. Let's work one at a time. First, 
. If we start at the positive x-axis and measure out 315 we end up in the 4th quadrant with a reference angle of 45 with the positive x-axis. The side across from the reference angle is -1, the side adjacent to the angle is 1, and the hypotenuse is sqrt2. The cotangent of this angle, then is 1/-1 which is -1. As for the second one, converting radians to degrees gives us that 
. Sweeping out that angle has us going around the origin more than once and ending up in the first quadrant with a reference angle of 30° with the positive x-axis. The side across from the angle is 1, the side adjacent to the angle is √3, and the hypotenuse is 2. Therefore, the secant of that angle is 2/√3.
Solve the equation below, and check the solution. 0.3x = 9 The solution set is { }
1 answer:
Answer:
{30}
Step-by-step explanation:
The solution set can be written a couple of ways:
<u>Roster</u>: lists the elements of the set:
x = {30}
<u>Set builder notation</u>: defines the elements of the set according to some rule or rules
{x : x = 30}
The latter form can have variations that define the domain of x on the left, such as
This is pronounced, "x is an element of the set of integers such that x is equal to 30." This sort of notation is more commonly used when the set is specified by an inequality or a functional relationship. You may see the colon (:) replaced by a vertical bar (|).
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<em>Comment on the above notations</em>
I don't like the notation x = {30} because the solution to the equation is a value, not a set of values. I prefer to write it as x ∈ {30}. "x is an element of the set containing 30." The "is an element of" symbol (∈) is not always available, so the equal sign is often used instead.
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