Answer:The degree measure of the second largest angle is 12, which is the second term in the ratio. The second largest angle is therefore 12/40 * 360 = <<12/40*360=108>>108 degrees.
Step-by-step explanation:The degree measures of the three angles of the triangle are in the ratio 7:12:21, so the sum of the measures of the three angles is 7 + 12 + 21 = <<7+12+21=40>>40.
The degree measure of the second largest angle is 12, which is the second term in the ratio. The second largest angle is therefore 12/40 * 360 = <<12/40*360=108>>108 degrees.