No, that's not right. Sadly, the answer you entered on the attached drawing is incorrect. It's slightly more complicated than that ... only slightly.
First, think about this for a second: What if the two GIVEN angles on the drawing had the same number of degrees ? Then by the method you've been using, you would subtract them from each other, and that would give you zero. So you would say that the last angle is zero degrees ? Can you see that this doesn't really work ?
Here's how it's really done:
It all rests on a rule about triangles. This is ALWAYS true, and you should memorize it:
When you add up the degrees of all three angles inside a triangle, the sum is ALWAYS 180 degrees.
So now, when you're given two of the angles, you know that the unknown one must be exactly enough to bring the sum of ALL of them up to 180 degrees.
Work it like this:
-- Take the two given angles. -- ADD them. -- Subtract their SUM from 180. Now you have the third angle.
In the drawing you attached:
-- The given angles are 39 and 102 . -- Add them: 39 + 102 = 141 -- Subtract the sum from 180: 180 - 141 = 39 . The unknown angle is 39 degrees.
But that's the same as one of the given angles ! ? :-( ? :-(
That's OK. It's perfectly fine for two of the angles, or sometimes even all three, to be the same size. They just have to all add up to 180 degrees, and everything is fine.
1/3 of an hour is 20mins multiply 1/2mile*2 and 20mins*2 1mile in 40mins. 1*2.25 40*2.25=90mins 2 1/4 miles in 90mins or an hour and a half That could also be writen as 2 1/4 miles in 3/2 hours or 1 1/2 hours
