# Can You Have A Negative Cosine?

## What is the rule for the third side of a triangle?

The Triangle Inequality Theorem states that the sum of any 2 sides of a triangle must be greater than the measure of the third side.

Note: This rule must be satisfied for all 3 conditions of the sides..

## What happens when sine is negative?

Both x and y coordinates are negative in the third quadrant. Since the hypotenuse is a +1, both the sine and the cosine must be negative. As the angle increases from 180° to 270°, the sine increases in magnitude but is now negative, so, the sine decreases from 0 to -1.

## Can an amplitude be negative?

The amplitude or peak amplitude of a wave or vibration is a measure of deviation from its central value. Amplitudes are always positive numbers (for example: 3.5, 1, 120) and are never negative (for example: -3.5, -1, -120).

## What quadrant is sin positive and COS negative?

In the first quadrant, the values for sin, cos and tan are positive. In the second quadrant, the values for sin are positive only. In the third quadrant, the values for tan are positive only. In the fourth quadrant, the values for cos are positive only.

## Why is the cosine of an obtuse angle negative?

Since the x axis is negative on the side and the cosine has the same sign as the x axis the cosine is negative. Cosine of an angle is defined as base/ hypotenuse. … Hypotenuse is always taken as positive. Hence Cos (obtuse angle) = base / Hypotenuse = Negative qty/ positive Qty.

## Where does sin equal?

Always, always, the sine of an angle is equal to the opposite side divided by the hypotenuse (opp/hyp in the diagram). The cosine is equal to the adjacent side divided by the hypotenuse (adj/hyp). What is the sine of B in the diagram?

## What does a negative cosine graph look like?

Hare – sign is in front of the cosine graph. If we draw the negative cosine it will produce the reflection about the x – axis. So the negative cosine graph will be opposite to the positive graph.

## Can a triangle have a negative side?

The sum of the two sides should always be greater than the length of one side in order for the figure to be a triangle. … Moreover, side lengths of triangles cannot be negative, so we can disregard this inequality.

## Why cosine of negative angle is positive?

Now the measure of the angle is -m, a negative value when measured clockwise is, because all angles have to be acute to apply the various trigonometrical ratios or relations. Hence, cosine of a negative angle changes into a positive value.

## What does sin to the negative 1 mean?

The inverse sin of 1, ie sin-1 (1) is a very special value for the inverse sine function. Remember that sin-1(x) will give you the angle whose sine is x . Therefore, sin-1 (1) = the angle whose sine is 1.

## What is the rule for triangle side lengths?

According to the first triangle inequality theorem, the lengths of any two sides of a triangle must add up to more than the length of the third side. This means that you cannot draw a triangle that has side lengths 2, 7 and 12, for instance, since 2 + 7 is less than 12.

Properties of Triangles Rule 3: Relationship between measurement of the sides and angles in a triangle: The largest interior angle and side are opposite each other. The same rule applies to the smallest sized angle and side, and the middle sized angle and side.

## What is F to the negative 1 power?

Notation. The inverse of the function f is denoted by f -1 (if your browser doesn’t support superscripts, that is looks like f with an exponent of -1) and is pronounced “f inverse”. Although the inverse of a function looks like you’re raising the function to the -1 power, it isn’t.

## What is negative cosine equal to?

cos(-θ) = cos θ & sin(-θ) = – sin θ. These are the negative angle identities. Although the diagram shows the angle θ in the first quadrant, the same conclusion can be reached when θ lies in any quadrant, and so the negative angle identities hold for all angles θ.

## What quadrants is sin negative?

The sine ratio is y/r, and the hypotenuse r is always positive. So the sine will be negative when y is negative, which happens in the third and fourth quadrants.

## What’s the difference between a sin and cos graph?

In a cosine graph, a positive or negative number vertically flips the graph and determines whether the graph starts at the maximum (if it’s positive) or minimum (if it’s negative). For a sine graph, a positive or negative number vertically flips the graph like it does with a cosine graph.

## How often does cosine repeat?

As the point P moves round the unit circle in either the clockwise or anticlockwise direction, the cosine curve above repeats itself for every interval of 360˚. Its period is 360˚.

## Is sin 1x the same as 1 Sinx?

The notation sin-1(x) has been misunderstood to mean 1/sin(x). … So sin-1(x) means the inverse sine of x, that is, the function that undoes the sine function. It is not equal to 1/sin(x).