Question

在Rt△ABC中,∠C=90°,AC:BC=1:2.求tanB,sinB,cosB.

在Rt△ABC中,∠C=90°,AC:BC=1:2.求tanB,sinB,cosB.

Answer 1

设AC为k.则BC为2K，由勾股定理得，AB为根号5K tanB=AC:BC=K;2K=1:2 SINB=AC：AB=1:根号5 COSB=BC:AB=2:根号5

Answer 2

tanB=2:1 sinB=1:根号5 cosB=2:根号5