How can i find the length of the base?

Remember, double the area and then divide by the known side length. To calculate the area of a triangle, we multiply the base times the height and divide by 2. If you are given the area, follow the steps backwards. You will multiply by 2 and divide by the given length.

x = 10.1

step-by-step explanation:

all of the angles of a tirangle add up to 180º

180 - 65 = 115 (since we already know the value of one angle)

(2x + 7) + (8x + 7) = 115

(combins like terms) 10x + 14 = 115

(isolate the variable subtract 14 from both sides): 10x = 101

(find the variable divide both sides by 10): x = 101/10

x = 10.1