{"id":9203,"date":"2022-01-03T02:06:50","date_gmt":"2022-01-02T20:36:50","guid":{"rendered":"https:\/\/mathemerize.com\/?p=9203"},"modified":"2022-01-03T02:13:06","modified_gmt":"2022-01-02T20:43:06","slug":"prove-that-1-tan2-theta-sec2-theta","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/prove-that-1-tan2-theta-sec2-theta\/","title":{"rendered":"Prove that 1 + \\(tan^2 \\theta\\) = \\(sec^2 \\theta\\)."},"content":{"rendered":"
In right angled triangle ABC,<\/p>\n
\\(sec \\theta\\) = \\(AC\\over AB\\) \\(\\implies\\) \\(sec^2 \\theta\\) = \\(AC^2\\over AB^2\\)<\/p>\n
\\(tan \\theta\\) = \\(BC\\over AB\\) \\(\\implies\\) \\(tan^2 \\theta\\) = \\(BC^2\\over AB^2\\)<\/p>\n
\\(\\implies\\) 1 + \\(tan^2 \\theta\\) = 1 + \\(BC^2\\over AB^2\\) = \\(AB^2 + BC^2\\over AB^2\\) = \\(AC^2\\over AB^2\\)<\/p>\n
[ By Pythagoras theorem, \\(AC^2\\) = \\(BC^2 + AB^2\\) ]<\/p>\n
\\(\\implies\\) 1 + \\(tan^2 \\theta\\) = \\(sec^2 \\theta\\)<\/p>\n","protected":false},"excerpt":{"rendered":"
Solution : In right angled triangle ABC, \\(sec \\theta\\) = \\(AC\\over AB\\) \\(\\implies\\) \\(sec^2 \\theta\\) = \\(AC^2\\over AB^2\\) \\(tan \\theta\\) = \\(BC\\over AB\\) \\(\\implies\\) \\(tan^2 \\theta\\) = \\(BC^2\\over AB^2\\) \\(\\implies\\) 1 + \\(tan^2 \\theta\\) = 1 + \\(BC^2\\over AB^2\\) = \\(AB^2 + BC^2\\over AB^2\\) = \\(AC^2\\over AB^2\\) [ By Pythagoras theorem, \\(AC^2\\) = \\(BC^2 + …<\/p>\n