Trigonometry

Cos3x formula in terms of cosx is as follows: 4cos3x-3cos x. In this post, we will also derive the cos3x formula in terms of sinx and give some examples. These formulas are very useful to solve trigonometric equations and simplify trigonometric expressions. Cos3x Formula Cos3x is the cosine function of a triple angle 3x. The … Read more

Tan2x formula in terms of tanx is as follows: $\dfrac{2\tan x}{1-\tan^2x}$. Here, we will also derive the tan2x formula in terms of sinx and cosx along with some examples. These formulas are very useful to solve trigonometric equations and simplify trigonometric expressions. Tan2x Formula Tan2x is the tangent function of a double angle 2x. The … Read more

Note that sin(cos-1 x) or sin(arc cosx) are algebraic functions, not trigonometric functions. The value of sin(cos-1 x) or sin(arc cosx) is equal to $\sqrt{1-x^2}$. In this post, we will simplify sin(cos^{-1} x). The formula of sin(cos inverse x) is given below: sin(cos-1 x) = root(1-x2). Simplify sin(cos-1(x)) We all know that $\sin(\cos^{-1}(x))= \sin(\text{arc} \cos … Read more

 The value of cos(sin^-1(x)) or cos(arc sin x) is equal to $\sqrt{1-x^2}$. In this post, we will simplify the expression $\cos(\sin^{-1}(x))$. Simplify cos(sin-1(x)) We note that both $\cos(\sin^{-1}(x))$ and $\cos(arc \sin x)$ have the same value. Thus to find out the value of $\cos(\sin^{-1}(x))$ or $\cos(arc \sin x)$, let us put $\theta=\sin^{{-1}} x$ $\cdots (\star)$ … Read more

In this blog post, we will learn how to simplify the trigonometric expressions cos4 x -sin4 x and cos4x+sin4x. We will apply the following two trigonometric identities: cos4x-sin4x Formula To simplify the expression cos4 x -sin4 x, we first apply the formula a2-b2 =(a-b)(a+b) with $a=\cos^2x$ and $b=\sin^2x$. Therefore, $\cos^4x-\sin^4x$ $=(\cos^2x)^2 – (\sin^2 x)^2$ $=(\cos^2x-\sin^2x)(\cos^2x+\sin^2x)$ … Read more

The value of the expression 1-sin^2(x) is equal to cos^2(x). In this post, we will find the formula of 1-sin^2x. 1-sin2x Formula To simplify the expression $1-\sin^2 x$, we will follow the below steps: Step 1: Let us apply the following Pythagorean trigonometric identity: $1=\sin^2 x +\cos^2 x$  $\cdots (\star)$ Step 2: Now, we substitute the value … Read more

The simplification of 1+tan2 x is equal to sec2 x. In this post, we will find the formula of 1+tan2x. This will be proved using trigonometric identities. 1+tan2x Formula To simplify the expression 1+tan2 x, we will follow the below steps: Step 1: At first, we put $\tan x=\dfrac{\sin x}{\cos x}$. By doing so, we … Read more

The value of cos(x-pi) is equal to -cosx. This can be done using the trigonometric formulas of compound angles. In this post, we will learn how to simplify cos(pi-x) and cos(x-pi). We will use the following formula on compound angles to find cos(pi-x) and cos(x-pi). $\cos(a-b)=\cos a \cos b +\sin a \sin b$ $\cdots (\star)$ … Read more

In this post, we will find the value of sin 75 degree, cos 75 degree, and tan 75 degree. They are very important in Trigonometry. Using their values, we are able to find the trigonometric values of many angles. We will now find the value of sine 75 degree. Value of sin 75 Answer: The … Read more