4 arc tan // - arc tan 239 d= arc tan {. ß= arc tan 239 Ło'c, tan 4α= tan (2α+2α) tan 20 = tan (α+ α) tan 2d = tan (d+d) Xand+tand tand tand = 144 25 719 = 5 25 tan 4α = tan (2α+2+) tanza+tanza (-tanza tanza (0 1- (20 119 の値を求めよ. 25 144 > tan d = 5. tan (4d-(³) = で (-== CaCE, -I - p² = ²² fet 考える = dan 40-tan 1+tan 40- tane (20 119 (+ (20 L 119 239 28680-119 28441 (+ 28561 28441 1 239 120 28441 28561 28441 tan (4α-B) = 1 + 4/ :. 4 arc tan = = - arctan 525/2 = 7 てC 239 4 tan ß = 23/9 [188. となる 4α-ß. (答) Gge