Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

C. equilateral

Step-by-step explanation:

A. right   means we have a 90 degree angle

B. scalene means all the sides have different lengths

C. equilateral  all the sides and all the angles are equal

D. isosceles  2 of the sides and 2 of the angles are equal

a_n = a_1 + (n - 1)d

the first term is 6.

the common difference d = ?

when you find d, replace n with 7 and d with the common difference to find your answer.