题目

What’s On? Electric Underground 7.30pm－1.00am   Free at the Cyclops Theatre Do you know who’s playing in your area? We’re bringing you an exciting evening of live rock and pop music from the best local bands. Are you interested in becoming a musician and getting a recording contract(合同)? If so, come early to the talk at 7.30pm by Jules Skye, a successful record producer. He’s going to talk about how you can find the right person to produce your music.  Gee Whizz 8.30pm-10.30pm   Comedy at Kaleidoscope Come and see Gee Whizz perform. He’s the funniest stand-up come如图，小兰想测量南塔的高度，她在处仰望塔顶，测得仰角为30°，再往塔的方向前进50 m至处，测得仰角为60°，那么塔高约为 _________ m.（小兰身高忽略不计，）