Hey, everyone. In this problem, we're asked to simplify the expression. And the expression we're given is the sine squared of theta minus the tangent squared of theta over the sine of theta plus the tangent of theta. Now remember that in order to fully simplify your equation, we want all of our arguments to be positive, which here, they already are. And we also don't want any fractions, which here, we do have one big fraction, so we want to get rid of it first. Now looking at my strategies here, we are constantly scanning for identities, but I don't really see any that will help me yet. But one of my other strategies is going to be to factor. And looking at the numerator that I have here, sine squared of theta minus the tangent squared of theta, you may recognize this as being a difference of squares. Because this is one term squared minus another term squared, so this will factor into the first term plus the second term times the first term minus the second term. So factoring that out, I can get the sine of theta, the first term, plus the tangent of theta, the second term, and then multiplying that by the sine of theta minus the tangent of theta. Now my denominator stays the same here, the sine of theta plus the tangent of theta. But here I notice that I can cancel something because this entire denominator is exactly what this first term is now in my numerator. So this fully cancels out and I've gotten rid of my fraction because now all I'm left with is the sine of theta minus the tangent of theta. So I have no fractions here. Now the other thing that tells us our expression is fully simplified is that we have as few trig functions as possible. Now here I have 2 trig functions but because they're being subtracted, it's going to be kind of hard to make it so that there are any fewer trig functions than are already there. So having these 2 trig functions is as few trig functions as I can have as possible. So we have also satisfied that last piece of criteria there, and we have fully simplified our trig expression down to the sine of theta minus the tangent of theta. Thanks for watching, and let me know if you have any questions.
sin2 − tan2 sin + tan = sin − tanTable of contents
- 0. Review of College Algebra4h 43m
- 1. Measuring Angles39m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
6. Trigonometric Identities and More Equations
Introduction to Trigonometric Identities
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