# How to solve (cos x + cos 3x) using trig identity?

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## How to solve (cos x + cos 3x) using trig identity?

Use trig identity to transform (cos x + cos 3x): F (x) = 2cos 2x.cos x + cos 2x = cos 2x (2cos x + 1 ) = 0. Next, solve the 2 basic trig equations. 2. Transform a trig equation F (x) that has many trig functions as variable, into a equation that has only one variable.

**How do you factor 3 out of 3 cos(x)?**

For a polynomial of the form a x 2 + b x + c a x 2 + b x + c, rewrite the middle term as a sum of two terms whose product is a ⋅ c = 2 ⋅ 1 = 2 a ⋅ c = 2 ⋅ 1 = 2 and whose sum is b = 3 b = 3. Tap for more steps… Factor 3 3 out of 3 cos ( x) 3 cos ( x).

### What is the transformation of cos x + cos 3x?

Use trig identity to transform (cos x + cos 3x): F (x) = 2cos 2x.cos x + cos 2x = cos 2x (2cos x + 1 ) = 0. Next, solve the 2 basic trig equations.

**What is the value of sin 2 θ + cos2 θ?**

\\sin^2 heta + \\cos^2 heta = 1. sin2 θ+cos2 θ = 1. In order to prove trigonometric identities, we generally use other known identities such as Pythagorean identities.

#### How many roots does f(x) have?

Because there is only one critical value, c, it can be said that f(x) has at most one root. Any feedback would be much appreciated. Thanks in advance calculus Share

**How do you solve trigonometric equations step by step?**

Step 1: Find the trigonometric values need to be to solve the equation. Step 2: Find all ‘angles’ that give us these values from step 1. Step 3: Find the values of the unknown that will result in angles that we got in step 2. Step 1: The only trig function in this equation is #sin#. Replace #sin (4x- pi/3)# by the single letter #S#.

## How to transform a trigonometric equation into a single variable?

Transform a trig equation F (x) that has many trig functions as variable, into a equation that has only one variable. The common variables to be chosen are: cos x, sin x, tan x, and tan (x/2) Solution. Call cos x = t, we get # (1 – t^2) (1 + 1 – t^2) = t^2#. Next, solve this equation for t. Note .

**What is the significance of infinity in calculus?**

Most students have run across infinity at some point in time prior to a calculus class. However, when they have dealt with it, it was just a symbol used to represent a really, really large positive or really, really large negative number and that was the extent of it.