Göster aşağıdaki kimliği kanıtlamak? 1 / cos290 + 1 / (sqrt3sin250) = 4 / sqrt3

Göster aşağıdaki kimliği kanıtlamak? 1 / cos290 + 1 / (sqrt3sin250) = 4 / sqrt3
Anonim

# LHS = 1 / (cos290 ^ @) + 1 / (sqrt3sin250 ^ @) #

# = 1 / (cos (360-70) ^ @) + 1 / (sqrt3sin (180 + 70) ^ @) #

# = 1 / (cos70 ^ @) - 1 / (^ @ sqrt3sin70) #

# = (Sqrt3sin70 ^ @ - cos70 ^ @) / (sqrt3sin70 ^ @ cos70 ^ @) #

# = 1 / SQRT3 (2 {sqrt3sin70 ^ @ - cos70 ^ @}) / (2sin70 ^ @ cos70 ^ @) #

# = 1 / SQRT3 (2 x 2 {sin70 ^ @ * (SQRT3 / 2) -cos70 ^ @ * (1/2)}) / (sin140 ^ @) #

# = 1 / SQRT3 (4 {sin70 ^ @ * cos30 ^ @ - cos70 ^ @ * sin30 ^ @}) / (sin (180-40) ^ @) #

# = 1 / SQRT3 (4 {sin (70-30) ^ @}) / (sin40 ^ @) = 1 / SQRT3 (4 {iptal (sin40 ^ @)}) / iptal ((sin40 ^ @)) = 4 / SQRT3 = RHS #

Bunu not et #cos (360-A) ^ @ = cosA ve sin (180 + A) ^ @ = - sinA #

# 1 / cos290 + 1 / (sqrt3sin250) #

# = 1 / cos (270 + 20) + 1 / (sqrt3sin (270-20)) #

# = 1 / sin20 - 1 / (sqrt3cos20) #

# = (sqrt3cos20-sin20) / (sqrt3sin20cos20) #

# = 2 / sqrt3 (sqrt3 / 2cos20-1 / 2sin20) / (sin20cos20) #

# = 4 / sqrt3 (sin60cos20-cos60sin20) / (2sin20cos20) #

# = 4 / sqrt3 günah (60-20) / (2sin20cos20) #

# = 4 / sqrt3 sin40 / sin40 #

# = 4 / sqrt3 #