SOLUTION: M and N are the midpoints of sides RS and RT of △RST, respectively. Given: RM = RN = 3x + 1 ST = 7x − 2 m∠R = 60° Find: x, RM, and ST

Algebra ->  Formulas -> SOLUTION: M and N are the midpoints of sides RS and RT of △RST, respectively. Given: RM = RN = 3x + 1 ST = 7x − 2 m∠R = 60° Find: x, RM, and ST      Log On


   



Question 1193077: M and N are the midpoints of sides
RS and RT of △RST, respectively.
Given:
RM = RN = 3x + 1
ST = 7x − 2
m∠R = 60°
Find:
x, RM, and ST

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

Given:
RM+=+RN+=+3x+%2B+1
ST+=+7x+-+2
m < R+=+60°
Find: x, RM, and ST
if you draw the triangle and label the sides you will see that the smaller triangle+RMN is an isosceles triangle because two of its sides are equal. So the base angles have to be congruent.
we can find the missing angles because we have measure of angle R+=+60 and we know that sum of interior angles in a triangle is 180.
Measure of angle RMN= measure of angle RNM=+%28180-60%29%2F2=60
you will see that all the three angles in triangle RMN are 60 each.
So it is an equilateral triangle.
Then the 3rd side MN is equal to the first two sides+RM and RN.
so we now have MN=+4x+%2B1
using triangle mid segment theorem, we know that the midsegment MN ( line connecting the midpoints of two sides of a triangle is midsegment) is parallel to ST and it’s length is half of the length of ST
MN+=++ST%2F2 or
ST+=+2+MN}
plug in the values
7x+-2+=+2%283x+%2B+1%29
7x+-2+=+6x+%2B+6
7x+-6x+=+2+%2B+6
x+=+8
then
RM+=+3%2A8+%2B+1=25
ST+=+7%2A8+-+2=54