Four rods, AB 20CM long, BC 22.5CM long, CD 25CM long and DA 27.5 long,b. the angle ADC
are pin-jointed at ABC and D. If the angle ABC is 120°, find
a. the distance AC
thankyou
a)
Using cosine rule...
AC^2 = 20^2 + 22.5^2 - 2*20*22.5Cos120 = 1356.25
AC = 36.8 cm
b)
Again using cosine rule...
36.8^2 = 27.5^2 + 25^2 - 2*27.5*25CosADC
2*27.5*25CosADC = 27.5^2 + 25^2 - 36.8^2
ADC = Cos^-1((27.5^2 + 25^2 - 36.8^2)/(2*27.5*25)) = 90.0 degrees
Hello, sa87uk!
Four rods: AB 20cm long, BC 22.5cm long, CD 25cm long, and DA 27.5 cm long,
are jointed at A, B, C, D.
If the angle ABC is 120°, find
a) the distance AC
b) the angle ADCCode:22.5 B o * * * o C * 120° * * * * * 20 * * * 25 * * * * * * A o * * * * * * * * * o D 27.5
Law of Cosines: .
. .
(a) Therefore: . cm
Law of Cosines: .
.
(b) Therefore: .
Edit: Too fast for me, Sean!