已知sinα=1/9,求[cos(α-5π)tan(2π-α)/cos(3π/2 +α)]+tan²α 值

题目

已知sinα=1/9,求[cos(α-5π)tan(2π-α)/cos(3π/2 +α)]+tan²α 值

答案

sin²α+cos²α=1所以cos²α=1-1/81=80/81[cos(α-5π)tan(2π-α)/cos(3π/2 +α)]+tan²α =[-cosα(-tanα)]/sinα+tan²α =cosα(sinα/cosα)/sinα+tan²α =1+tan²α=1+sin&...