What is the lateral side of an isosceles triangle with area 20 unit^2 and base 10 units?

Step 1: Make a note of the known and unknown measurements
Step 2: Use formula of area of isosceles triangle to write
FORMULAS:
Area of an isosceles triangle = \frac{1}{2} b*h
Where b - base and h - height (altitude)
h (Altitude) = \sqrt{a^2 - \frac{b^2}{4}}
Step 3: Substitute the known values in the area formula.
EXAMPLE: Area of an isosceles triangle = \frac{1}{2} b*h
20 = \frac{1}{2} 10 * h
Step 4: Simplify the equation and find the unknown value (Height)
EXAMPLE : h = \frac{20}{5}
h = 4
Step 5: Set up a formula to calculate the lateral side of an isosceles triangle.
NOTE: Isosceles triangle is a combination of two right triangle
Pythagoras theorem
FORMULA:(lateral\ side)^2=(height)^2+\left(\frac{base}{2}\right)^2
Step 6: Find the lateral side of an isosceles triangle.
EXAMPLE: (lateral\ side)^2=4^2+(\frac{10}{2})^2
lateral\ side=\sqrt{16+25}
lateral\ side=\sqrt{41}