Question 925254
<pre>
We want to know how many degrees the ? stands for in this
triangle, which is drawn to scale:

{{{drawing(400,250,-.5,1.5,-.5,.75,locate(.05,.08,"63°"),
locate(.6,.08,"12°"),locate(.12,.22,"?°"),
triangle(.2679491924*cos(63*pi/180),.2679491924*sin(63*pi/180),0,0,1,0) )}}}

We know that the three angles in EVERY triangle has sum 180°.

So we add the two angles that we are given:

63°+12° = 75°

Then we subtract from 180°:

180°-75° = 105°

We get that the third angle is 105°, and now we can 
complete our drawing:

{{{drawing(400,250,-.5,1.5,-.5,.75,locate(.05,.08,"63°"),
locate(.6,.08,"12°"),locate(.1,.2,"105°"),
triangle(.2679491924*cos(63*pi/180),.2679491924*sin(63*pi/180),0,0,1,0) )}}}

Edwin</pre>