Modern Geometry

Question

Find the length of RS if S is the midpoint of RT, RS = 3x-3 and ST = 2x +6

Answer 1

      3x-3              2x+6

R--------------S----------------T

 

Since S is the midpoint, RS = ST:

 

3x - 3 = 2x + 6

 

Subtract 2x from both sides

 

x - 3 = 6

 

Add 3 to both sides:

 

x = 9

 

RS = 3x-3 = 3*9 - 3 = 27 - 3 = 24

 

As a check, ST should also equal 24:

 

ST = 2x+6 = 2*9 + 6 = 18 + 6 = 24