#Solving for angles in diagram involving circles and triangles

22 messages · Page 1 of 1 (latest)

round schooner
#

Please answer om founding a and b. Thanks

glass fjordBOT
zinc umbra
#

(2) is solvable but (1) is unsolvable

peak bridge
glass fjordBOT
zinc umbra
#

i can also give full explanation or just let you solve it by giving hints

#

we will use this diagram to solve the question

#

∠CAB = 2∠CDB { angle subtended by chord at the centre of the circle is twice the angle subtended by chord at circumference of the circle.}
angle is subtended by chord CB

#

∠CAB = 71

#

∠ACB = ∠ABC {Angles opp to equal sides}
As, AC = AB {equal radii}

#

∠ABC + ∠ACB + ∠CAB = 180 {Angle sum property of triangle}

#

2∠ABC + 71 = 180
2∠ABC = 109
∠ABC = 109/2 = 54.5

peak bridge
#

maybe wanna get OP's feedback first?

#

or not, sorry for intruding either way.

glass fjordBOT
#

Solving for angles in diagram involving circles and triangles

zinc umbra
#

Now,
∠DAE = ∠FAB
∠FAB = 55

#

Now, ∠AFB = ∠ABF {Angles opp to equal sides} ---(1)
As, AF = AB {equal radii}

#

so we can get,
∠AFB + ∠ABF + ∠ FAB = 180
From this we get.
2∠AFB + 55 = 180
2∠AFB = 125
∠AFB = 62.5

#

so , ∠ABF = 62.5
∠ABF = ∠FBC + ∠ ABC
putting values of angles we get
62.5 = a + 54.5
a = 8

zinc umbra
#

(2) Hence, a = 8 and b = 62.5