Find the value of 3 in the triangle shown below.

Since the lengths of the two sides are equal (3.5), you can tell that this is an isosceles triangle. So, both of the base angles (55°) must be equal. Additionally, you know that the sum of the three angles in a triangle must equal 180°. Therefore, x would equal 70°.

Here's the math:

55° + 55° = 110°

180° - 110° = 70°

x = 70°

TO VERIFY:

70° + 55° + 55° = 180°

step-by-step explanation:

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.