CBSE Class 10 Sample Paper for 2018 Boards
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CBSE Class 10 Sample Paper for 2018 Boards
Last updated at December 16, 2024 by Teachoo
This is a question of CBSE Sample Paper - Class 10 - 2017/18.
You can download the question paper hereΒ https://www.teachoo.com/cbse/sample-papers/
Transcript
Question 6 If cos A = 2/5 , find the value of 4 + 4 tan2 A Given cos A = 2/5 (ππππ ππππππππ‘ π‘π β π΄)/π»π¦πππ‘πππ’π π = 2/5 π΄π΅/π΄πΆ=2/5 Let AB = 2x & AC = 5x Using Pythagoras theorem to find BC (Hypotenuse)2 = (Height)2 + (Base)2 AC2 = AB2 + BC2 (5x)2 = (2x)2 + (BC)2 (BC)2 = (5x)2 - (2x)2 (BC) 2 = 25x2 β 4x2 (BC) 2 = 21x2 BC = β(21π₯^2 ) BC = β21 π₯ Now, tan A = (ππππ πππππ ππ‘π π‘π β π΄)/(ππππ ππππππππ‘ π‘π β π΄) tan A = π΅πΆ/π΄π΅ tan A = (β21 π₯)/2π₯ tan A = β21/2 Thus, 4 + 4 tan2 A = 4 + 4 (β21/2)^2 = 4 + 4 Γ 21/4 = 4 + 21 = 25
