Thursday

September 18, 2014

September 18, 2014

Posted by **Chris** on Sunday, October 30, 2011 at 3:06am.

(1) B*sin(kl/sqr2) = D*sin(kl)

(2) (k/sqr2)*B*cos(kl/sqr2) = (k)*D*cos(kl)

-Form matrix of these 2 equations and solving the determinant=0 will lead to: (1/sqr2)*cos(kl/sqr2)*sin(kl) - sin(kl/sqr2)*cos(kl)= 0

-How do i solve this?

- Engineering -
**drwls**, Sunday, October 30, 2011 at 6:36amI do not see why the determinant must be zero. Your final equation is a statement that it IS zero, except you seem to have left out an "l" term after the first k in equation 2.

You final equation is of the form

a*cosA*sinB -sinA*cosB = 0

a = tanA/tanB

where a = 1/sqrt2

A = k*l/sqrt2

B = k*l

You may have to solve for kl by iteration. I don't see an easy way.

- Engineering -
**MathMate**, Sunday, October 30, 2011 at 8:03amIf it's of any help, here's a plot of the function

f(x)=sqrt(2)*cos(x)*sin((x)/sqrt(2))-sin(x)*cos((x)/sqrt(2))

http://imageshack.us/photo/my-images/196/1319958400.png/

Since there is only one variable, and the graph is harmonic, there's probably a way to solve the equation, but I cannot think of one for now. Use iteration as drwls suggested for the moment.

**Answer this Question**

**Related Questions**

Math(check) - Solve 1= (y+3)(2y-2) Use foil on the right side. 1 = 2y^2 +6y -2y...

Math(Please help) - 2) Use the sum and difference identites sin[x + pi/4] + sin[...

Math(Please help) - 1)tan Q = -3/4 Find cosQ -3^2 + 4^2 = x^2 9+16 = sqrt 25 = 5...

tigonometry - expres the following as sums and differences of sines or cosines ...

Math - Solving for Trig Equations - Solve the following equation for 0 less than...

TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...

Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...

trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...

algebra - Can someone please help me do this problem? That would be great! ...

trigonometry HELP pleasE! - these must be written as a single trig expression, ...