Urgent: the formula for the circumference of a circle is c=2 pi r. use 3.14 for pi. solve the formula for r. what is the radius of a circle with a circumference of 87 cm? round the the nearest tenth. show your work. a- c over 2 pi; 13.9cm b- 2 pi over c; 27.7cm c- 2 pi c; 546.4cm d- c - 2 pi; 80.7cm the formula for the area of a triangle is a = bh over 2. solve the formula for h. what is the height of a triangle that has an area of 25 mi^2 and a base with a length of 10 mi? show your work. round to the nearest tenth. a- h=2ab; 1.25 mi b- h=2ab; 2.5 mi c- h=2a over b; 0.2 mi d- h=2a over b; 5 mi