What's sin ABC if AB=BC=25 and AC=30
Law of Cosines
AC^2 = AB^2 + BC^2 - 2 (AB * BC)cos (ABC)
30^2 = 25^2 + 25^2 - 2 (25 * 25)cos (ABC)
[ 30^2 - 25^2 - 25^2 ] / [ -2 (25*25) ] = cos (ABC)
7 / 25 = cos (ABC)
sin (ABC) = sqrt [ 25^2 - 7^2 ] / 25 = sqrt [ 576 ] / 25 = 24 / 25
