I don't know if my answer is completely correct, but I think it's 100. All triangles add up to 180, and an isosceles triangle has 2 equal sides. 40 would be the 2 sides, and 180 subtracted from 80 equals 100.
To calculate the <span>surface area of a composite figure you must apply the formulas for calculate the area of each figure that is part of the composite figure and then, you must sum all the areas calculated.
For example, is the composite figure is form by a triangle and rectangle, the surface area of the composite figure will be:
SA= Area of the triangle+ Area of the rectangle= (bh/2)+bh</span>
Answer:
the answer is 67!! I think I asked my teacher and thats what they said.
Step-by-step explanation:
Answer:
11 yrs
Step-by-step explanation:
Mean = sum of ages/number of ages
Let the age of the seventh girl be A
Given the addition of the age of the seventh girl will make the mean of the ages be 13,
So,
13 = 17+8+12+15+15+13+A/7
Add up the ages
13 = 80 + A /7
Cross multiply
80 + A = 13 x 7
80 + A = 91
Subtract 80 from both sides to isolate A
80 - 80 + A = 91 - 80
A = 11
The age of the seventh girl is 11
