the measures of two of the sides of an equilateral triangle are 3x+15 inches and 7x-5 inches. what is the measure of the third side in inches?
a. 5
b. 1
c. 18
d. 30
Since an equilateral triangle has all three sides equal in length, we can equate the expressions for the measures of the two sides:
3x + 15 = 7x - 5
Subtracting 3x from both sides:
15 = 4x - 5
Adding 5 to both sides:
20 = 4x
Dividing both sides by 4:
x = 5
Substituting this value back into either of the expressions for the measures of the sides:
3(5) + 15 = 30
Therefore, the measure of the third side of the equilateral triangle is 30 inches.
The answer is d. 30.