Hello everyone! I’m also a math learner. For me, trigonometric formulas are the most basic array in the curriculum. However, some students still feel it difficult to memorize all these formulas? Don’t worry! Today, I would like to introduce to you one simple method to remember these formulas for a long time with APP *RESUMIND*. Let’s scroll down to the blue text for detailed instructions!

## 1. Tips to learn Trigonometric Formulas super-fast: Basic trigonometric formulas

- sin
^{2}x + cos^{2}x = 1 - tan x = sin x / cos x
- cot x = cos x / sin x
- tan x * cot x = 1
- 1 / cos
^{2}x = 1 + tan^{2}x - 1 / sin
^{2}x = 1 + cot^{2}x

## 2. Tips to learn Trigonometric Formulas super-fast: The addition formula

- sin(a + b) = sin a * cos b + cos a * sin b
- cos(a + b) = cos a * cos b – sin a * sin b
- In short, sin = sin cos + cos sin, cos = cos cos – sin sin
- tan(a + b) = (tan a + tan b) / (1 – tan a * tan b)

## 3. Tips to learn Trigonometric Formulas super-fast: The multiplication formula and the downgrade formula.

- sin 2x = 2 * sin x * cos x
- cos 2x = cos
^{2}x – sin^{2}x - sin x * cos x = sin 2x / 2
- sin
^{2}x = (1 – cos 2x) / 2 - cos
^{2}x = (1 + cos 2 x) / 2 - sin 3x = 3 * sin x – 4 * sin
^{3}x - cos 3x = 4 * cos
^{3}x – 3 * cos x

The multiplication formula and the downgrade formula.

## 4. The formula converts the product to the sum.

- cos a * cos b = [ cos(a + b) + cos(a – b) ] / 2
- sin a * sin b = -[ cos(a + b) – cos(a – b) ] / 2
- sin a * cos b = [ sin(a + b) + sin(a – b) ] / 2

the conversion formula

## 5. The formula converts the sum to the product.

- cos a + cos b = 2 * cos [(a + b) / 2] * cos [(a – b) / 2]
- cos a – cos b = – 2 * sin [(a + b) / 2] * sin [(a – b) / 2]
- sin a + sin b = 2 * sin [(a + b) / 2] * cos [(a – b) / 2]
- sin a – sin b = 2 * cos [(a + b) / 2] * sin [(a – b) / 2]
- Way to remember quickly:
- cos + cos = 2 cos cos
- cos – cos = – 2 sin sin
- sin + sin = 2 sin cos
- sin – sin = 2 cos sin

## 5. How to memorize quickly with *RESUMIND*

*RESUMIND*helps you learn well.

*RESUMIND* is a subconscious development application installed on the mobile phone. This app bases on human biology and works for anyone. Humans have a mechanism: While you are dreaming in sleep, if there is a word emits, it will be remembered by the brain for a long time. Therefore, *RESUMIND* will give you a way to memorize trigonometric formulas very simply without spending much time.

*Let’s copy trigonometric formulas**into the application. Then set the time until you almost wake up in the morning that is when your brain is the most conscious. Although you do not take much time to learn, the knowledge is still “loaded” into your brain. What is better than this? Please install the application for yourself. Have a good time!*

**APP: REPROGRAM SUBCONSCIOUS MIND** helps in self-development and studying while sleeping. It evokes powerful sources of energy every day through sight and hearing. Therefore, Please use **APP: REPROGRAM SUBCONSCIOUS MIND** because it’s awesome.