# the COMPLEX relationship between tan^-1(x) and tanh^-1(x) | Summary and Q&A

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November 21, 2018
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blackpenredpen
the COMPLEX relationship between tan^-1(x) and tanh^-1(x)

## TL;DR

The video discusses integrating 1 over 1 plus x squared in both the real and complex world, resulting in inverse tangent and inverse hyperbolic tangent functions.

## Key Insights

• βΊοΈ Integrating 1 over 1 plus x squared in the real world gives the inverse tangent function, while integrating 1 over 1 minus x squared in the complex world gives the inverse hyperbolic tangent function.
• π The process of factoring difference of two squares is used in the complex world integration.
• π Performing a u substitution helps transform the complex world integral to the new world.
• π The constant values in the real and complex world integrals can be determined through equating and solving.

## Transcript

okay that's to summer for fun here we're going to integrate 1 over 1 plus x squared and I'll show you guys the results in the real world and also in the complex world especially during the complex Rock pay close attention to it because maybe you can do that on your calculus 1 what calculus 2 final exam where you encounter similar question anyway be... Read More

### Q: How is the integral of 1 over 1 plus x squared represented in the real world?

In the real world, the integral of 1 over 1 plus x squared is represented as the inverse tangent of x plus a constant.

### Q: How is the integral of 1 over 1 minus x squared represented in the complex world?

In the complex world, the integral of 1 over 1 minus x squared can be represented by factoring difference of two squares and using the inverse hyperbolic tangent function.

### Q: How can the integral in the complex world be transformed to the new world?

By performing a u substitution, where u is equal to ix, the integral in the complex world can be transformed to the new world, resulting in the inverse hyperbolic tangent of ix plus a constant.

### Q: How can the constant in the complex world integral be determined?

The constant in the complex world integral can be determined by equating the results in the real world and complex world, and solving for the constant value.

## Summary & Key Takeaways

• The video demonstrates integrating 1 over 1 plus x squared in the real world, which results in the inverse tangent of x plus a constant.

• The video then explores integrating 1 over 1 minus x squared in the complex world, which utilizes the concept of factoring difference of two squares and leads to the inverse hyperbolic tangent function.

• By performing a u substitution, the integral is transformed to the new world, resulting in the inverse hyperbolic tangent of ix plus a constant.