{"id":11674,"date":"2022-08-14T01:47:11","date_gmt":"2022-08-13T20:17:11","guid":{"rendered":"https:\/\/mathemerize.com\/?p=11674"},"modified":"2022-08-14T01:47:18","modified_gmt":"2022-08-13T20:17:18","slug":"in-triangle-abc-right-angled-at-b-it-tan-a-1over-sqrt3-find-the-value-of-i-sin-a-cos-c-cos-a-sin-c-ii-cos-a-cos-c-sin-a-sin-c","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/in-triangle-abc-right-angled-at-b-it-tan-a-1over-sqrt3-find-the-value-of-i-sin-a-cos-c-cos-a-sin-c-ii-cos-a-cos-c-sin-a-sin-c\/","title":{"rendered":"In \\(\\triangle\\) ABC right angled at B, it tan A = \\(1\\over \\sqrt{3}\\), find the value of (i) sin A cos C + cos A sin C (ii) cos A cos C – sin A sin C"},"content":{"rendered":"
Consider a \\(\\triangle\\) ABC, in which \\(\\angle\\) B = 90<\/p>\n
For \\(\\angle\\) A, we have :<\/p>\n
Base = AB, Perp. = BC,\u00a0 and\u00a0 \u00a0Hyp. = AC,<\/p>\n
tan A = \\(\\perp\\over base\\) = \\(BC\\over AB\\) = \\(1\\over \\sqrt{3}\\)<\/p>\n
Let BC = k and AB = \\(\\sqrt{3} k,<\/p>\n
AC = \\(\\sqrt{{AB}^2 + {BC}^2}\\) = 2k<\/p>\n
\\(\\therefore\\)\u00a0 \u00a0sin A = \\(\\perp\\over hyp.\\) = \\(BC\\over AC\\) = \\(k\\over 2k\\) = \\(1\\over 2\\)<\/p>\n
and,\u00a0 cos A = \\(base\\over hyp.\\) = \\(AB\\over AC\\) = \\(\\sqrt{3}k\\over 2k\\) = \\(\\sqrt{3}\\over 2\\)<\/p>\n
For \\(\\angle\\) C, we have :<\/p>\n
Base = BC, Perp = AB and Hyp. = AC,<\/p>\n
\\(\\therefore\\)\u00a0 \u00a0sin C = \\(\\perp\\over hyp.\\) = \\(AB\\over AC\\) = \\(\\sqrt{3}k\\over 2k\\) = \\(\\sqrt{3}\\over 2\\)<\/p>\n
and,\u00a0 cos C = \\(base\\over hyp.\\) = \\(BC\\over AC\\) = \\(k\\over 2k\\) = \\(1\\over 2\\)<\/p>\n
(i)<\/strong>\u00a0 sin A cos C + cos A sin C = 1<\/p>\n (ii)<\/strong>\u00a0 cos A cos C – sin A sin C = 0<\/p>\n","protected":false},"excerpt":{"rendered":" Solution : Consider a \\(\\triangle\\) ABC, in which \\(\\angle\\) B = 90 For \\(\\angle\\) A, we have : Base = AB, Perp. = BC,\u00a0 and\u00a0 \u00a0Hyp. = AC, tan A = \\(\\perp\\over base\\) = \\(BC\\over AB\\) = \\(1\\over \\sqrt{3}\\) Let BC = k and AB = \\(\\sqrt{3} k, AC = \\(\\sqrt{{AB}^2 + {BC}^2}\\) = 2k …<\/p>\n