Trigonometry! #48

Geometry Level 4

Find all values of θ \theta in the interval ( π 2 , π 2 ) \left (-\frac {\pi}{2} , \frac {\pi}{2} \right) satisfying the equation ( 1 tan θ ) ( 1 t a n θ ) sec 2 θ + 2 tan 2 θ = 0 (1-\tan \theta)(1-tan \theta)\sec ^{2} \theta + 2^{\tan^{2} \theta} = 0

Enter the product of the sum of the measure(s) of θ \theta in degrees and 2.

This problem is part of the set Trigonometry .


The answer is 0.

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2 solutions

Satvik Choudhary
Apr 2, 2015

It can be clearly seen that all the terms are positive as the trignometric functions are squared and the exponent function gives only positive values. For the equation to be equal to 0 both the terms (the trigo and the exponent) must bw individually 0 which is not possible for the exponent function. So the equation has no solution.

Omkar Kulkarni
Feb 14, 2015

( 1 + tan θ ) ( 1 tan θ ) sec 2 θ + 2 tan 2 θ = 0 (1+\tan\theta)(1-\tan\theta)\sec^{2}\theta+2^{\tan^{2}\theta}=0

( 1 t a n 2 θ ) ( 1 + tan 2 θ ) + 2 tan 2 θ = 0 (1-tan^{2}\theta)(1+\tan^{2}\theta)+2^{\tan^{2}\theta}=0

1 tan 4 θ + 2 tan 2 θ = 0 1-\tan^{4}\theta+2^{\tan^{2}\theta}=0

Substituting tan 2 θ \tan^{2}\theta with x x , we have

x 2 1 = 2 x x^{2}-1=2^{x}

Now if we check these graphs, we get the only solution, ( 3 , 8 ) (3,8) .

tan 2 θ = 3 θ = ± π 3 \therefore \tan^{2}\theta=3 \Rightarrow \boxed{\theta = \pm\frac{\pi}{3}}

The question is not correct as your solution. Correct it.

Trishit Chandra - 6 years, 3 months ago

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No, I asked for the product of the sum of the solutions ( π 2 + π 2 = 0 ) \left(-\frac{\pi}{2}+\frac{\pi}{2}=0\right) and 2.

Omkar Kulkarni - 6 years, 2 months ago

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Please correct your question , its not matching with your solution.

Ankit Kumar Jain - 4 years, 2 months ago

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