Thursday

September 18, 2014

September 18, 2014

Posted by **Chiquesta** on Saturday, December 17, 2011 at 12:59am.

z^n + 1/z^n = 2cosntheta

z^n - 1/z^n = 2 isin ntheta

1. Express sin^5theta in the form Asintheta + Bsin3theta + Csin5theta and hence find the integral of sin^5theta.

2. Express sin^6theta in multiples of costheta and hence evaluate the integral of sin^6theta between 0 and pi/2.

3. Evaluate the integral of cos^7theta between pi/2 and 0.

The answers are:

1. -1/80cos5theta + 5/48cos3theta - 5/8costheta

2. 5pi/32

3. 5pi/32

Could you please guide me through the solutions, thank you SO much :)

- Math - complex numbers -
**drwls**, Saturday, December 17, 2011 at 2:41amIf you had posted one at I time, I could have helped with one of them. It is past my bedtime here.

When you say "between pi/2 and 0" do you mean from pi/2 to zero? That would be backwards.

Please be more specific.

- Math - complex numbers -
**Chiquesta**, Saturday, December 17, 2011 at 3:36amSorry, yes I meant from 0 to pi/2 for the last two questions.

**Answer this Question**

**Related Questions**

precal - De Moivre’s theorem states, “If z = r(cos u + i sin u), then zn = rn(...

Pre-Calculus - Can someone please help me with this problem? De Moivre’s theorem...

Calculus - Determine the polar form of the complex number 3 - 2i. Express the ...

Complex angles - There are four complex fourth roots to the number 4−43&#...

trig - Use De Moivre's theorem to simplify the expression. Write the answer in ...

Math (Trigonometry [Polar Form]) - Let z be a complex number such that z = 2(cos...

Trigonometry - There are four complex fourth roots to the number 4−4√...

pre-calculus - Graph each complex number. Then express it in rectangular form. 2...

Math - use Demoivre's Theorem to find the indicated power of the complex number...

Math - use Demoivre's Theorem to find the indicated power of the complex number...