Question

M angle D=? What is the degree of the angle?

Answer 1

80°

Explanation:

In ACB and ECD

AC =~ CE [ Given ]

BC =~ CD [ Given ]

<ACD =~ <ECD [ Vertical angles ]

Hence, ∆ ACB =~ ECD by SAS congruency of triangles.

Then, <B = <D

In ∆ABC , sum of all three angles must be 180°

<A + <B + <C = 180°

plug the values

`30 + < d \: + 70 = 180`

Add the numbers

`100 + < d = 180`

Move constant to R.H.S and change it's sign

`< d = 180 - 110`

Subtract the numbers

`< d = 80` °

Hope this helps..

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