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2. (3分)用计算器求(精确到0.0001):
(1)sin 5° 12'≈0.0906
(2)cos 18° 40'≈0.9474
(3)tan 18° 36'≈0.3365
12. (8分)已知三角函数值，求锐角(精确到1").
(1)已知sin a=0.5018，求锐角a;
(1)30° 7'9"
(2)已知tanθ=5，求锐角θ.
(2)78° 41'24"
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2. (3分)用计算器求(精确到0.0001):
(1)sin 5° 12'≈0.0906
(2)cos 18° 40'≈0.9474
(3)tan 18° 36'≈0.3365
12. (8分)已知三角函数值，求锐角(精确到1").
(1)已知sin a=0.5018，求锐角a;
(1)30° 7'9"
(2)已知tanθ=5，求锐角θ.
(2)78° 41'24"
