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DAB = DBA = x
Triangle DCB has angles of 40, 40, 100.
So, x + 40 = 90 => x = 50 (B)
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AD = DB, DC = CB, and angle ABC = 90º as shown above, then what is the value of xº

In triangle CBD,
CD = CB
angle CDB = angle CBD (isosceles triangle)
100 +2y = 180
2y = 80
y=40

In triangle ABD,
AD = BD
angle DAB = angle DBA
Also given
angle CBA = 90
angle DBA = 90 -40 =50
x = 50

IMO B
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Two equal angles in Triangle BDC are \(\frac{(180-100)}{2} = 40\)
X= 90 - 40 = 50
Option B

Bunuel

If AD = DB, DC = CB, and angle ABC = 90º as shown above, then what is the value of xº?

A. 40º
B. 50º
C. 65º
D. 80º
E. 100º

Attachment:
1.png
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Bunuel

If AD = DB, DC = CB, and angle ABC = 90º as shown above, then what is the value of xº?

A. 40º
B. 50º
C. 65º
D. 80º
E. 100º

Attachment:
The attachment 1.png is no longer available

Simply fill the angle to find x: IMO B

Follow the diagram
Attachments

PB07.PNG
PB07.PNG [ 8.23 KiB | Viewed 2079 times ]

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In triangle DCB, since DC = CB, therefore angle CDB = angle CBD = 40 (sum of all angles in the traingle is 180)

Angle B is 90 hence and angle CBD is 40 so angle DBA is 90 - 40 = 50.

Since AD = DB, therefore angle DAB = angle DBA = 50 (angle opposite to equal sides are equal)

Therefore, x = 50

Answer B
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