Book error, or am i missing something? TRIG piece

rygza
In the attached picture there is a right triangle (the right angle is on the right bottom corner). The angle, theta, is on the left-most side. From what i remember, sin (theta) is equal to opposite/hypotenuse. If you can see in the picture, it has written: delta x = h/sin(theta)

so, sin(theta) = h/delta x

isn't this wrong?

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• 2011-01-22_20.00.04.jpg
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JaredJames
The difference between X0 and X1 is delta x, which is the hypotenuse.

h is the height, which is the opposite part of sin(theta)=opposite/hypotenuse

So in this case, sin(theta) = h / delta x. Or to get the hypotenuse, delta x = h / sin(theta). The book is correct.

It is a poor choice of notation to use h in this case, as it is slightly confusing. However, h denotes the vertical height not the hypotenuse (which is delta x).

rygza
The difference between X0 and X1 is delta x, which is the hypotenuse.

h is the height, which is the opposite part of sin(theta)=opposite/hypotenuse

So in this case, sin(theta) = h / delta x. Or to get the hypotenuse, delta x = h / sin(theta). The book is correct.

It is a poor choice of notation to use h in this case, as it is slightly confusing. However, h denotes the vertical height not the hypotenuse (which is delta x).

but wouldn't delta x be the length of the bottom side? and then the hypotenuse would be = sqrt((delta x)^2 + (h)^2)

JaredJames
No, look where X0 and X1 are on the picture. The line between those points is delta x - which is the hypotenuse.

rygza
No, look where X0 and X1 are on the picture. The line between those points is delta x - which is the hypotenuse.

OOH yes now it makes sense :rofl: I miss one little thing and it costs me 30minutes lol

THANK YOU!