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Right Triangle Sides

Date: 09/14/98 at 22:45:53
From: Bobbi
Subject: Identifying opposite and adjacent.

I'm in grade 10 pre-calc math and usually everything comes really 
easily when it comes to math, but I'm having a tough time with 
trigonometry. I use SOHCOHTOA but I need help finding out which sides 
are opposite and adjacent.

Date: 09/25/98 at 21:33:58
From: Doctor Whitworth
Subject: Re: Identifying opposite and adjacent.

Dear Bobbi:

Opposite and adjacent sides depend on the angle to which they refer:

In a right angle triangle, look at the angle in question. This must be 
one of the angles that is NOT the right angle (which is also called 
the 90 degree angle). One side that meets your angle is the hypotenuse, 
which is on a diagonal and directly across from the right degree angle. 
The other side that meets your angle is called the adjacent side.
                           /  |
                         /    |
                       /      |
                     /        |
       hypotenuse  /          | opposite
                 /            |
               /              |  
             /            |---|
           / angle        |   |
         /----------------|---| right angle

The angle is made up of two sides. One side will always be the 
hypotenuse. The other side is always called the adjacent.

The third side of the triangle, which is neither the adjacent nor the 
hypotenuse (so that it never goes near the angle) is called the 
opposite side, since it usually lies across from the angle in 
the question.

I hope this helps you to understand the problem you are dealing with.

Good luck with your course and I hope you do your very best. Please 
let us know if we can help you again.


- Doctor Whitworth, The Math Forum   
Associated Topics:
High School Trigonometry

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