It’s easy to make a tablet stand with corrugated fiberboard (aka corrugated paper). To customize view angle, I use Google Calculator and trigonometric functions to do the math.

# Design Draft

First, I disassemble a corrugated paper box and draw a design draft:

# Trigonometric Functions

Here is what I have already known:

- Max length (A+B+C+D) of corrugated paper.
- A is equal to tablet height.

At first, I just let b (length of B) = c (length of C) = d (length of D) = (total length – tablet height) / 3. Then I get a stand with 60° view angle according to an equilateral triangle.

How to customize * θ*? I decide to let b = c to make it a Isosceles triangle.

Based on Pythagorean theorem, I get * d = 2b * cosθ* or use the formula below:

You need a scientific calculator which supports trigonometric functions here. Because my Sony Xperia C3‘s build-in calculator doesn’t support Inverse trigonometric functions, I decide to install Google Calculator after reading 10 best calculator apps for Android on Android Authority.

# Google Calculator

Launch and swipe left, you see more functions and operators. There is a DEG (degree) or RAD (radian) on the upper left. Click to select the unit you need.

If you want to calculate * θ* with a given d, you need to use inverse trigonometric functions. In some calculators, there is a Inv (inverse) button to help you switch from sine to arcsine (or sin¯¹(x)) and vice versa. But in Google Calculator, you need to tap and hold for about 0.5 second. It enters the inverse trigonometric function automatically as below:

# My Tablet Stand

Here is a photo of my tablet stand. It helps me to recall trigonometric functions and Pythagorean theorem learned in junior high school. They are very helpful in engineering!

# Reference

- Android Authority: 10 best calculator apps for Android
- Google play: Calculator
- Sony: Xperia C3 Specifications
- Wiki: Corrugated fiberboard
- Wiki: Degree (angle)
- Wiki: Equilateral triangle
- Wiki: Inverse trigonometric functions
- Wiki: Isosceles triangle
- Wiki: Pythagorean theorem
- Wiki: Radian
- Wiki: Scientific calculator
- Wiki: Trigonometric functions