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# Right triangle trigonometry — Harder example

Watch Sal work through a harder Right triangle trigonometry problem.

## Want to join the conversation?

• What is the meaning to have line WZ?
• As Sal remarks at , line WZ is not needed; they just put it there to trick you, :) Is that what you meant?
• Doesn't adjacent side mean the base of the triangle, and the opposite side means the perpendicular of the triangle.
So we should actually use the sine function to solve the above question.
• "Adjacent side" doesn't always mean the base of the triangle. In fact, in a pure visual sense, the base of the triangle is kind of arbitrary, since we can rotate the triangle to make either of the two legs of the triangle the base. In reality, the side that is "adjacent" is relative to the angle you want to find the cosine of. In the image you provided, the sides that are labeled adjacent and opposite are labeled that way relative to angle A. Notice how the adjacent side touches angle A, and the opposite side doesn't touch angle A. If the image was talking about angle B, then the base of the triangle becomes the opposite side instead of the adjacent one (since it doesn't touch angle B).

In the video, Sal calls the perpendicular of the triangle the adjacent angle since it's the side that touches the angle he's interested in. It doesn't matter if it's at the bottom of the triangle or not - in fact, you could rotate the triangle in the video 90 degrees counterclockwise and get something that looks exactly the same as the image you provided.
• I do not live in America but I was curious, at what age and grade do students take the SAT
• Around the age of 16-17. In 11th grade. Some in 12th although it’s not advisable.
• can you write angle CBD as sin(90-34) = cos(34) and subtract both of them = 0? or am i missing something
• You can! That would be a faster, more advanced way to solve the problem, and every bit at legitimate.
• Another way to solve this question would have been to write angle CBD as (90-34) degrees then sin(90-34) would be equal to cos(34) as sin(90-x)=cos(x) and then the expression would become cos(34)-cos(BAC) and since BAC is also 34 the final expression would be cos(34)-cos(34) which would be equal to 0
• are we allowed to use a calculator for this?
• Sal used the calculator, so it most likely means that we're allowed to use it.
• At in the video, why does he multiply by h instead of divide by 5.3?
• Because multiplying by H makes "H cosine 58"(H x 0.5299) equal to 5.3. It's impossible to divide H by 0.5299 because you can't divide a letter by a number. Hope this clears things up!
• What do co,sin, and tan mean?