76 Area of ellipse (given major and minor axes) 77 Major axis or transverse diameter of ellipse (given area and minor axis) 78 Sum of interior angles of polygon (given number of sides) 79 Number of sides of a simple closed polygon (given sum of internal angles) 80 Median line length of trapezoid (given lengths of the parallel sides) 81 Base of Trapezoid (given median line length and the other base) 82 Interior angle of equilateral polygon (given number of edges) 83 Length of internal common tangent of two circles (given distance between centers and radius) 84 Exterior common tangent of two circles (given distance between centers and radius) 85 Area of a convex quadrilateral (given diagonals and angle) 86 Diagonal length of a convex quadrilateral (given area,angle and another diagonal) 87 Area of Trapezoid (given lengths of parallel sides and height) 88 Length of one parallel side of trapezoid (given area, base and height) 89 Height of Trapezoidal (given area and lengths of parallel sides) 90 Area of circle (given radius) 91 Radius of circle (given area) 92 Perimeter of circle (given radius) 93 Radius of circle (given perimeter) 94 Area of circular sector (given radius and angle) 95 Radius of circular sector (given area and angle) 96 Central angle of circular sector (given area and radius) 97 Area of rhombus using trigonometry (given edge and angle) 98 Area of triangle (given two sides and angle) 99 Area of rhombus (given base and height) 100 Perimeter of circular sector (given radius and central angle) 