1 Answer

Selfsimilar · Answer 1 · 2023-12-03T02:44:03+0000

Recall that the interior angles of a triangle add up to 180 degrees, then:

$m\angle A+m\angle B+m\angle C=180^(\circ)\text{.}$

Now, recall that a right angle measures 90 degrees.

Then we can set the following equation:

$m\angle A+15^(\circ)+90^(\circ)=180^(\circ).$

Adding like terms we get:

$m\angle A+105^(\circ)=180^(\circ).$

Subtracting 105 degrees from the above equation we get:

$\begin{gathered} m\angle A+105^(\circ)-105^(\circ)=180^(\circ)-105^(\circ), \\ m\angle A=75^(\circ). \end{gathered}$

Answer:

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