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△STR≅△LMN, SR=7b+8, and LN=11b−12. Find b and SR

a) b = 3 and SR = 67
b) b = 5 and SR = 43
c) b = 5 and SR = 67
d) b = 3 and SR = 43

1 Answer

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Final answer:

To find the variable b and the length of side SR, set the expressions 7b+8 and 11b-12 equal to each other, solve for b, which is 5, and then substitute this into the expression for SR to get the length of 43.

Step-by-step explanation:

The student's question involves determining the value of the variable b and the length of side SR given that triangles △STR and △LMN are congruent with SR and LN as corresponding sides. According to the given information, SR equals 7b+8 and LN equals 11b−12. Since the triangles are congruent, these two expressions must be equal.

To find the value of b, set the expressions equal to each other:

  • 7b + 8 = 11b − 12

Now, solve for b:

  • 7b + 8 = 11b − 12
  • 8 + 12 = 11b − 7b
  • 20 = 4b
  • b = 5

Substitute b = 5 into the expression for SR to find its length:

  • SR = 7(5) + 8
  • SR = 35 + 8
  • SR = 43

Therefore, the correct answer is (b) b = 5 and SR = 43.

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