Question

I need help with this please

Answer 1

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:

`75.0.`