Question

Parallel line geometry

Answer 1

Answer: Angle 1 is 80 degrees

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Explanation:

See the diagram below. I've extended one of the rays to form a full line. This is shown in red. The alternate interior angles 60 and x are congruent due to the parallel lines, so x = 60.

We can then find angle y

x+y+20 = 180 ... angles of a triangle add to 180

60+y+20 = 180

y+80 = 180

y = 180-80

y = 100

Use this to find z

y+z = 180

100+z = 180

z = 180-100

z = 80

Or you could use the remote interior angle theorem

x+20 = z

60+20 = z

80 = z

z = 80