Question

show that 7 sec^2 20-7tan^2 20=7

Answer 1

Answer:

HERE IS YOUR ANSWER:

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A/c question,

$7 {sec}^{2}20 - 7 {tan}^{2}20 = 7$

L.H.S,

$7( {sec}^{2}20 - {tan}^{2}20)$

using formula,

$\ {tan}^{2} \alpha + 1 = \: {sec}^{2} \alpha$

then,

${sec}^{2} \alpha - {tan}^{2} \alpha = 1$

$7 ({sec}^{2}20 - {tan}^{2}20 )$

$7(1) \\ = 7$

hope this helps you ✔