Si us plau, resoldreu q 18?

Si us plau, resoldreu q 18?
Anonim

Donat que # A + B = 90 ^ @ # llavors # A = 90-B ^ @ #

#rarr (tanAtanB + tanAcotB) / (sinAsecB) - (sin ^ 2B) / (cos ^ 2A) #

# = (tanA tanB + cotB) / (sinAsecB) - (sin ^ 2B) / (cos ^ 2 (90 ^ @ - B) #

# = ((cancel (sinA) / cosA) sinB / cosB + cosB / sinB) / (cancel·la (sinA) / cosB) - (sin ^ 2B) / (sin ^ 2B) #

# = ((1 / cosA) (sin ^ 2B + cos ^ 2B) / (sinB * cancel (cosB))) / (1 / cancel (cosB)) - 1 #

# = 1 / (cos (90 ^ @ - B) sinB) -1 #

# = 1 / sin ^ 2B-1 = (1-sin ^ 2B) / sin ^ 2B = (cos ^ 2B) / (sin ^ 2B) = cot ^ 2B #

Donat que # A + B = 90 ^ @ # llavors A = 90-B ^ @ #

Ara

# (tanAtanB + tanAcotB) / (sinAsecB) - (sin ^ 2B) / (cos ^ 2A) #

# (tan (90 ^ @ - B) tanB + tan (90 ^ @ - B) cotB) / (sin (90 ^ @ - B) secB) - (sin ^ 2B) / (cos ^ 2 (90 ^ @ - B)) #

# = (cotBtanB + cotBcotB) / (cosBsecB) - (sin ^ 2B) / (sin ^ 2B) #

# = 1 + bressol ^ 2B-1 = cotx ^ 2B #