Posted by **lizzie** on Tuesday, January 22, 2008 at 5:35pm.

there is a problem on my paper in which there is a right angle forming a triangle. the right angle is to the right end of the triangle. at the vertex at the end of the left side, those two lines go on to make two more angles. how do i figure out the degree of those angles.

ex. if m<10=30*, then m<13 = ?

- geometry -
**Damon**, Tuesday, January 22, 2008 at 5:50pm
Are you telling me that you have a right triangle and one of the other angles measures 30 degrees?

If that is the case, all you need to know is that the interior angles of any triangle add up to 180 degrees, a straight line, and you know that the measure of a right angle is 90 degrees

so if one of the angles is 30

then 30 + x + 90 = 180

so the third angle is 60 degrees

However I may have your picture wrong. If you are talking about the angles formed at the left vertex OUTSIDE the triangle, what you need to know is that a straight line is 180 degrees.

this means that if the interior angle on the left is 30 degrees, the one to its left is 180 - 30 = 150 degrees

then the next one counterclockwise is 180 - 150 = 30 degrees (This angle is opposite the one inside the triangle and if you have had the theorem about opposite angles are equal, you would have said the answer right away)

the next one counterclockwise is 180 - 30 again or 150 again and then we are back around the circle to the interior 30 degree angle

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