Question

Find angle B if triangle ABC below is isosceles. 

A: 77 Degrees 
B: 36 Degrees 
C: 50 Degrees 
D: 44 Degrees 

Answer 1

so these will equal each other so put them to equal to find x
2x-20=x+8
   +20     +20
2x=x+28
 -x    -x
x=28 now plug it in 
2(28)-20= 36
(28)+8= 36, since they're equal this make it an isosolece and it's correct 
So the answer is B. hope this helped you have a great day!!

Answer 2

Use the Isosceles Triangle Theorems. The Base Angles Theorem. If two sides of a triangle are congruent, then the angles opposite those sides are congruent. Converse of the Base Angles Theorem. So, X + 8 = 2X - 20
                         subtract x from both sides    -X         -X
                           new equation                           8 = X - 20
                     add 20 to both sides                    +20     +20
                                                                         28 = X
Angle B =    X + 8        
sub 28 for X   (28 + 8 =  36)