Solving+Trig+Equations

media type="youtube" key="L_9v2k0gSgI" height="344" width="425" =Solving Trig Equations by: Petra Hartman, Kara Kelly, Lexi Miller-Golub,=

*make sure your calculator is in the right setting, either radians or degrees depending on the problem you are on
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 * know your unit circle

There are multiple steps in finding the solutions in trig equations, if given this problem: 2sinx - 1 = 0 you would go about solving this by 2sinx - 1 = 0 <- adding 1 to the other side +1 +1

__2__sinx = __1__ <- dividing 2sinx by 2 2 2

sinx = 1/2 <- this will result with sinx being equal to 1/2

sinx^-1 = 30 <- then you will find the inverse of sinx being 30 degrees

There can also be different situations when solving trig equations, such as double angles and

For solving trig equations with double angles, take this example:

Sinx - Cos2x = 0 sinx - (1 - 2sinx^2) = 0 <- use identities to change cos2x into 1 - 2sin^2 2sinx^2 - sinx - 1 = 0 <- move the problem around to have it look like a quadratic (2sinx -1)(sinx +1) = 0 <- at this point you can now factor it sinx = 1/2 sinx = -1 <- now solve both for sinx sinx = {30, 150, 270} <- find all quadrants it can appear in.

another example with steps:

cos2+cos+1=0 cos^2-sin^2+cos+1=0 2cos^2-1+cos+1=0 2cos^2+cos=0 cos(2cos+1)=0 cos=0 and 2cos+1-0 therefore the solutions are 90, 270, 120 and 240

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