Question

If ABCD is a rectangle, and ABD=55, what is the value of X?

Answer 1

x= 70

Explanation:

This question needs an attachment; see attached

Given

ABD = 55

Required

Find x?

In the figure shown in the attachment, angle b and ABD are alternate interior angles;

From parallel and perpendicular line theorems; alternate interior angles are equal.

This implies that <b = 55

Also; when a rectangle is divided by two diagonals, the resulting triangles are isosceles triangles;

where 2 sides and 2 angles are equal;

This implies that <b = <c = 55

Sum of angles in a triangle = 180;

So,

<x + <b + <c = 55

x + 55 + 55 = 180

x + 110 = 180

Subtract 110 from both sides

x + 110 - 110 = 180 - 110

x = 180 - 110

x = 70