设BC中点为E,连接AE
则BE=EC=5,
∵AB=AC,且E为中点
∴AE丄BC
∴AE^2+BE^2=AB^2
∴AE=12
(1)
sinC
=AE/AC
=12/13
(2)
∵∠CBD+∠C=90°
∠C+∠CAE=90°
∴∠CBD=∠CAE
∴sin∠CBD
=sin∠CAE
=EC/AC
=5/13.
设BC中点为E,连接AE
则BE=EC=5,
∵AB=AC,且E为中点
∴AE丄BC
∴AE^2+BE^2=AB^2
∴AE=12
(1)
sinC
=AE/AC
=12/13
(2)
∵∠CBD+∠C=90°
∠C+∠CAE=90°
∴∠CBD=∠CAE
∴sin∠CBD
=sin∠CAE
=EC/AC
=5/13.