This question is from trigonometry
Topic – Trigonometric ratios on. complementary angles
We have to prove that sec70°sin20° + cos20°cosec70° = 2 without using trigonometric tables
RS Aggarwal, Class 10, chapter 12, question no 2(iii).
Rajan@2021Guru
Without using trigonometric tables, prove that: sec70°sin20° + cos20°cosec70° = 2
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LHS
sec70°sin20° + cos20°cosec70°
= sec(90° – 20°) sin20° + cos20° cosec(90° – 20°)
= cosec 20° sin20° + cos20° sec 20°
= 1 +1
= 2 = RHS