# What is cos pi by 2 theta?

## What is cos pi by 2 theta?

cos(2+)=sin is proved by the formula cos(a+b)=cosacosbsinasinb .

## What is the value of sin pi by 2 theta?

Yes, sine is directly related to the y axis. When an angle intersects the unit circle, the sin is equal to the y value of the point at which it intersects. Sine (theta+pi/2) is equal to cosine.

**What is the value of Cos Pi Theta?**

cos( – ) = -cos, tan( – ) = -tan, cot( – ) = -cot.

### Does cos increase or decrease as increases from 90 to 180?

As the angle increases from 90 to 180, the cosine increases in magnitude, but is now a negative value. The cosine goes from 0 to -1.

### Why is tan 90 undefined?

At 90 degrees we must say that the tangent is undefined (und), because when you divide the leg opposite by the leg adjacent you cannot divide by zero. In the third quadrant the hypotenuse extended will now meet the tangent line above the x-axis and is now positive again.

**Can Sines be negative?**

As a result, sine will be positive, but cosine will be negative, and all tangent values will be negative.) The final quadrant is the fourth quadrant, and there, all x values are positive, but all y values are negative, so sine will be negative, cosine will be positive and tangent values will be negative.

## Why does sin theta equal Theta?

When a anlge tends to zero. When you are using the mensure in radians and theta are really small, you can say sin(angle) equals the angle. In the case of sin theta being equal to theta, all other trigonometric functions are also equal to theta, and this when the value of theta is very small.

## How do you know if COS is negative?

2:55Suggested clip · 38 secondsWhere is Sine/Cosine Positive or Negative? – YouTubeYouTubeStart of suggested clipEnd of suggested clip

**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.

### Can Arccos be negative?

The arccosine of a positive number is a first quadrant angle, cos-1(+) is in quadrant I. The arccosine of zero is /2, cos-1(0) is /2. The arccosine of a negative number is a second quadrant angle, cos-1(-) is in quadrant II.

### What do you do if theta is negative?

7:11Suggested clip · 117 secondsTrigonometry – Negative angle identities – YouTubeYouTubeStart of suggested clipEnd of suggested clip

**How do you find sin theta?**

2:48Suggested clip · 100 secondsTrigonometry – Find the exact value of sin cos and tan – YouTubeYouTubeStart of suggested clipEnd of suggested clip

## What does sin to the negative 1 mean?

Inverse Sin 1 and sin-1(-1) 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.

## Is sin even or odd?

Sine is an odd function, and cosine is an even function. You may not have come across these adjectives “odd” and “even” when applied to functions, but it’s important to know them. A function f is said to be an odd function if for any number x, f(–x) = –f(x).

**Is CSC odd or even?**

Cosine and secant are even; sine, tangent, cosecant, and cotangent are odd. Even and odd properties can be used to evaluate trigonometric functions.

### Is there a function that is both even and odd?

A function with a graph that is symmetric about the origin is called an odd function. Note: A function can be neither even nor odd if it does not exhibit either symmetry. Also, the only function that is both even and odd is the constant function f(x)=0 f ( x ) = 0 .

### Is Tan an odd or even function?

Cosine and secant are even; sine, tangent, cosecant, and cotangent are odd. Identities can be used to evaluate trigonometric functions.

**How can you tell if a function is odd?**

You may be asked to “determine algebraically” whether a function is even or odd. To do this, you take the function and plug –x in for x, and then simplify. If you end up with the exact same function that you started with (that is, if f (–x) = f (x), so all of the signs are the same), then the function is even.

## How do you tell if a trig function is odd or even?

The graph is symmetric with respect to the origin therefore it is on odd function. The graph is symmetric to the y- axis therefore it is an even function. The majority of functions are neither odd nor even, however, sine and tangent are odd functions and cosine is an even function.