數學!! 急!!!!! 唔該~~~今日內要

若 sinA = 9/41 , cos(A+B) = 7/25 ,且A,B 均為銳角,試求sinB 的值
已知 sinA = 9/41 , ∴ cosA = 40/41, ∵A為銳角,
cos(A+B) = 7/25 , ∴ sin(A+B) = 24/25, ∵A+B之和少于90ﾟ
cosAcosB - sinAsinB = 7/25
40/41 cosB - 9/41 sinB = 7/25...............(1)
sinAcosB + sinBcosA = 24/25
9/41 cosB + 40/41 sinB = 24/25..............(2)
解 (1) 和 (2)

cosB =496/1025
sinB = 897/1025