Bored with such Questions but good enough For you to Solve!

Geometry Level 3

Find the smallest positive value of $x$ such that ${ 8 }^{ 1+\cos x + \cos^2x + \cos^3x + \ldots} = 64.$

\pi /2

All of These

2\pi

\pi /6

\pi /3

\pi /4

None of These

3\pi

1 solution

Department 8
Nov 17, 2015

Nice question Hrisheek Yadav.

First of all we see the power of 8 is a sum of an infinite GP so

$\Large{8^{\frac{1}{1-\cos{x}}}=64\\ \frac{1}{1-\cos{x}}=2 \\ \cos{x}=\frac{1}{2}}$

The first positive value of $x$ such that $\cos{x}=\frac{1}{2}$ is at $\frac{\pi}{3}$

Same way!!

Dev Sharma - 5 years, 6 months ago

Did the same way.

Shreyash Rai - 5 years, 6 months ago

Tum logo ki aisi ki taisi, Harisem aur tu ana fiitjee mero ge dono

Department 8 - 5 years, 6 months ago

hahahaha.. What happened?

Dev Sharma - 5 years, 6 months ago

@Dev Sharma – They hacked in my brilliant account. (Black Hacking)

Department 8 - 5 years, 6 months ago

@Department 8 – how did they do it?

Dev Sharma - 5 years, 6 months ago

@Dev Sharma – Well I logged in my friend's mobile and solved questions and logged out and he used some computer programming to hack my password again.

Department 8 - 5 years, 6 months ago

@Department 8 – they were following all people??

Dev Sharma - 5 years, 6 months ago

What is the real name of asdfgh Rfcv? LOL

Nihar Mahajan - 5 years, 6 months ago

@Nihar Mahajan – his real name is kaustubh miglani

Department 8 - 5 years, 6 months ago

Bored with such Questions but good enough For you to Solve!

1 solution

0 pending reports