# What Is The Integral of sin^2x? (“sin Square x”)

What Is The Integral of Sin²x? It is like finding the inverse of a derivative. In this sense, integrations are anti-derivatives. Integration is adding parts to find the whole. The whole pizza is integrated, whereas the slices are the individual functions that can be integrated. Suppose f(x) is any function and f′(x) is its derivative. The integration of f′(x) with respect to dx is given by

$$∫ f′(x) dx = f(x) + C.$$

Integrals can be expressed in two ways. Integrals of an indefinite function are integrals of a function when there is no limit to the integration. They contain an arbitrary constant. Definite Integrals: An integral of a function with limits of integration. The interval of integration has two values. The lower limit is one and the upper limit is the other. There is no constant integration.

## Integral of sin²x

Integrating sin²(x) is not an option, so we have to change it into another form, which we can easily do by using trig identities. Integration of sin square will be based on the concept of cos double angles.

$$sin²(x)$$
$$cos(2x) = 1 – 2sin²(x)$$ [From cos double angle Trigonometric identities] $$sin²(x) = (1/2)(1 – cos(2x)$$
Integrate on both the sides
$$∫sin²(x)dx = ∫(1/2)(1 – cos(2x) dx$$
$$=(1/2) × ∫(1 – cos(2x)) dx$$
$$= 1/2 × (x – 1/2sin(2x)) + C$$
Thus, $$∫sin2(x) dx = (1/2)x – (1/4)sin(2x) + C$$

Hence,the final integral of sin2x is $$(1/2)x – (1/4)sin(2x) + C$$

## Step By Step Guide To Find Integral of sin²x

$$∫sin²(x)dx$$
• Use Pythagorean Identities: $$sin²x=1/2−cos2x/2$$
$$∫(1/2−cos2x/2)dx$$
• Use Sum Rule: $$∫f(x)+g(x)dx=∫f(x)dx+∫g(x)dx.$$
$$∫(1/2)dx−∫(cos2x/2)dx$$
• Use this rule: $$∫adx=ax+C$$
$$x/2−∫(cos2x/2)dx$$
• Use Constant Factor Rule: $$∫cf(x)dx=c∫f(x)dx.$$
$$x/2−1/2∫(cos2x)dx$$
Let u=2x, du=2dx, then , dx= (1/2) du
• Using u and du above, rewrite$$∫cos2xdx$$.
$$∫(cosu)/2du$$
• Use Constant Factor Rule: $$∫cf(x)dx=c∫f(x)dx.$$
$$1/2∫cosudu$$
• Use Trigonometric Integration: the integral of cosu is sinu.
$$(sinu)/2$$
• Substitute u=2x back into the original integral.
$$sin2x/2$$
The integral should be rewritten after the substitution has been completed.
$$x/2−sin2x/4$$
$$x/2−sin2x/4+C$$

### How do you integrate sin2x?

So, now we have to integrate sin 2x

$$∫sin 2x dx = ½ ∫2 × sin(2x) dx (i)$$

Let us assume u = 2x. Then, du = 2dx.

We know that $$∫sin x = − cos x + C$$

Hence on substituting, equation (i) becomes

$$∫sin 2x dx = ½ ∫sin(u) du$$

$$∫sin 2x dx = ½ (– cos u du) + C$$

$$∫sin 2x dx = −½ cos(2x) + C$$

Thus, $$∫sin 2xdx = −½ cos (2x) + C$$

### What can sin 2x equal?

The Sin2x formula is another double angle formula. With this formula, we can find the sine of an angle whose value has been doubled. We know that sin is one of the primary trigonometric ratios that define the length of the opposite side of an angle to that of the hypotenuse in a right-angled triangle. With the use of basic trigonometric formulas, there are many formulas associated with sin 2x. The range of the sin function is [-1, 1], so the range of sin2x is also [-1, 1].

Sin 2x is the double angle identity for sine in trigonometry. Angular relationships are studied in trigonometry by comparing angles and sides of right-angled triangles. There are two simple formulas for sin 2x:

$$sin(2x) = 2 sin x cos x$$ (in terms of sin and cos)

$$sin(2x) = (2tan x)​/(1 + tan2x)$$ (in terms of tan)

These are the main formulas of sin 2x. But we can write this formula in terms of sin x (or) cos x alone using the trigonometric identity sin2x + cos2x = 1. They are

$$sin 2x = 2 √(1 – cos2x) cos x$$ (sin 2x formula in terms of cos)

$$sin 2x = 2 sin x √(1 – sin2x)$$ (sin 2x formula in terms of sin)

### Why is sin 2pi 0?

To find the value of sin of 2pi, let us first recall the sine function for different standard angles from the trigonometric table. sin 0 = 0, sin π/6 = 1/2, sin π/4 = √2/2, sin π/3 = √3/2, and sin π/2 = 1. This table does not contain the value of sin 2pi. Various methods will be used here to find that sin of 2pi is 0. A few examples will also be given to illustrate how this works.

Sin of 2pi is 0. i.e., sin 2π = 0. Using the trigonometric table, we can find the trigonometric ratios of the standard angles 0, π/6, π/4, π/3, and π/2. This table does not give us the value of sin of 2pi. Trigonometric ratios of nonstandard angles are most commonly found by using the reference angles and quadrant where the angle lies. 2pi can also be found this way. Several other methods can be used to find the value of sin of 2pi, including

• Using double angle formula
• Using reference angle
• Using unit circle

We will prove that sin 2π = 0 in each of these methods.

The sin of 2pi is 0.

The sin of 2pi Using Double Angle Formula

We can find the value of sin of 2pi using the double angle sine formula, which is sin 2x = 2 sin x cos x. Because we must determine the value of sin(2π), we should substitute x = π in the above formula. It then gives us:

sin 2π = 2 sin π cos π -(1)

Since π is also a non-standard angle, we find the values of sin π and cos π using the sum and difference formulas. Then we get

sin π = sin (π/2 + π/2) = sin π/2 cos π/2 + cos π/2 sin π/2 = (1)(0) + (0)(1) = 0

cos π = cos (π/2 + π/2) = cos π/2 cos π/2 – sin π/2 sin π/2 = (0)(0) – (1)(1) = -1

Substitute these values in (1),

sin 2π = 2 (0) (-1) = 0

Hence, sin of 2pi = 0.

Sin of 2pi Using Reference Angles

When we convert 2π into degrees, we get 360°. 360° lies in the interval [0°, 360°], so its coterminal angle itself is the reference angle. If we subtract 360° from it, we find the coterminal angle. If we divide 360° by 360°, we get 0°. Therefore, the coterminal angle of 360° is 0°. Also, 360° means one full rotation, so it comes either in the first quadrant or the fourth quadrant. So, we’ll take both cases into consideration.

• First Quadrant: We know that in the first quadrant, sin is positive.
Then sin 360° = + sin 0° = 0 (because sin 0° = 0)
• Fourth Quadrant: We know that in the fourth quadrant, sin is negative.
Then sin 360° = – sin 0° = 0 (because sin 0° = 0)

From both the cases, sin 360° = sin 2π = 0.

Hence, sin 2π = 0.

The sin of 2pi Using Unit Circle

Let us recall a few points about the unit circle before finding the value of sin of 2pi.

• A unit circle is a circle of radius centered at its origin.
• A point on the unit circle corresponds to an angle.
• The angle is formed by the line joining the origin and the point with the positive direction of the x-axis in an anticlockwise direction.
• If P(x, y) corresponds to some angle θ, then x = cos θ and y = sin θ. In other words, the sine of the angle represents the y-coordinate of the point.

A circle of 0° on the unit circle consists of 2π, which is just 360° and represents one full rotation, so it is nothing but the angle made by the x-axis and itself. The unit circle’s point (1, 0) is also on the x-axis, so we know that 0° corresponds to the same point. Thus,

sin 2π = sin 0° = y-coordinate of (1, 0) = 0.

Hence, sin 2π = 0.

### What is the cos2x formula?

The relationship between an angle and its sides is explained by the trigonometric ratios of an angle in a right triangle. So what does cos2x mean? In addition to the cosine 2x or cos 2x formula, there is also the double angle formula or cos 2x formula. The formula has a double angle in it, which is why it’s called a double angle formula. It is driven by these trigonometric functions of the sum and difference of two numbers (angles) and related expressions. Now that we understand what the cos 2x formula is, we can move on to learn more about trigonometry and the formula of cos2x.

Now if you are wondering what the formula of cos2x is, let me tell you that we have 5 cos x formula.

• The trigonometric formula of $$cos2x = Cos²x – Sin²x$$
• The trigonometric formula of $$cos2x = 1 – 2Sin²x$$
• The trigonometric formula of $$cos2x = 2Cos²x – 1$$
• The trigonometric formula of $$cos2x = (1−tan²x)/(1+tan²x)$$
• The trigonometric formula of $$cos2x = (Cos²x−Sin²x)/(Cos²x+Sin²x)$$