Из формулы \( S=\frac{a b c}{4 R} \) выразите переменную \( c \).

Find the area of a parallelogram \( A B C D \) whose bese \( B C \) is 27 cm and altitude \( A E \) is 8 cm . If the lengh of the altitude \( A F \) to the base \( C D \) is 12 cm . Find \( C D \).

1. \( \triangle A B C \) is right angled at \( A \). \( A D \) is perpendicular to \( B C \). If \( A B=8 \mathrm{~cm}, B C=10 \mathrm{~cm} \) and \( A C=6 \mathrm{~cm} \). Find the area of \( \triangle A B C \). Also, find the length of \( A D \).

9. In the given figure \( D L \) and \( B M \) are the heights corresponding to sides \( A B \) and \( A D \) respectively of parallelogram \( A B C D \). If the area of parallelogram is \( 300 \mathrm{~cm}^{2}, A B=30 \mathrm{~cm} \) and \( A D=20 \mathrm{~cm} \). Find the length of \( B M \) and \( D L \).

14. Find the radius of a hemisphere of volume \( 80 \mathrm{~cm}^{3} \)

An equilateral triangle it's perimeter equals 27 cm , then it's side length is......