In the given figure, O is the centre of the circle, BD=OD and CD is perpendicular to AB. Find angle CAB
Answers
Answer = Given : O is the center of the circle BD=OD and CD | AD
To determine : ∆CAB
Construction = join OC
Determination : BD=OD
:. ∆DOE = ∆DBE
| Angle opposite to equale side of triangle are equal
In angle ∆OED and angle ∆BED,
∆DOE =∆DEB | from above
∆DEO = ∆DBE
| Each =90° (given ) as CD | AB
OD=BD | given
:. ∆OED = ∆BED
| AAS congruence rule
:. OE = BE | C.P.C.T
Now, in ∆CEO and ∆CEB ,
CE = CE | common
∆CEO and ∆CEB | each 90°
OE = BE | proved above
:. ∆CEO =~ ∆CEB
|SAS congruence rule
:. CO = CB .... (1)
∆ACB = 90°
| Angle in a semi circule is a right angle
| OA = OB = OC ....(2)
| The mid point of the hypotenure of a right angled triangle is equidistant from its vertices
Frome (1) and (2)
OB= OC = BC
:. ∆OBC is equilateral triangle is 60°
= 2 ∆ BAC = 60°
The angle subtanded by an arc of circle at the center is twice the angle substended by it at any point on the remaining part of circle
= ∆BAC = 30°
= ∆CAB = 30°
Step-by-step explanation:
Answer:
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