# Calendar: 1889-1890 Page 753

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ENGINEERING DEPARTMENT 107 11 Find the values to places of decimal fractions of cos 15c and cos 135 12 man at the instant of dropping from balloon appears to spectator on the ground at an elevation such that tan θ At what elevation will he appear when half way down What fraction of his descent will he have accomplished when he appears at an elevation 13 Prove that in any triangle cos JB -f bcosA ν tan 11 ---- -- tan iii cot cotj cot6r b2- -c2 a2 c2- -a2- a2- -b2-c2 14 If ζ are in Arithmetical Progression prove that tana tany tan tan χ tan tan ζ tan tany tan ζ tan ζ tan tan χ tany Plane antt ertial Cngonometri Find from figure cos 60 and tan 30 Writedown cos 240 tan 330 An equilateral triangle ABC and square Β CD Ε are on opposite sides ofBC and AF is perpendicular to ΈΒ produced prove from the triangle AEF that tan 75 V3 Prove that cos 2A cos 2A sin and deduce that cos 2A tall cos cos Prove-- cos and solve the cos equation tan tan Show that in any plane triangle a2 b2 -f2 £2 fo cos Jf are two lines 15 inches and 25 inches long respec- tively inclined to each other at an angle ACB 30 on AC are described externally square ACDE and square BCFG having centres Ο and Ρ respectively find the length of OP The angular elevation of the top of building is observed from certain point to be 60 on walking 100 feet directly Β

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