Two angles of a triangle measure 55° and 20°. What is the measure of the third angle of the triangle?
A. 159
B. 90°
O C. 1050
D. 2859
HELP

The three angles of a triangle always add up to 180.

Therefore, we have the equation:

55+20+x=180.

Solving for x, we get x=105.

So the answer is C.

Hope this helps! :D

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4