Answer:
m∠ABC = 67.5°
BC = =6.888301782572 cm
Step-by-step explanation:
ABC is an isosceles triangle
Then
m∠ABC = m∠ACB
The sum of the interior angles of a triangle is equal to 180°
Then
m∠ABC + m∠ACB + m∠BAC = 180°
Then
m∠ABC + m∠ACB + 45 = 180°
Then
2 × m∠ABC = 180°
Then
m∠ABC = (180−45)÷ 2 = 67.5°
Law of SIN :
[tex]\frac{9}{\sin \left( 67.5\right) } =\frac{BC}{\sin \left( 45\right) }[/tex]
[tex]BC=\frac{9}{\sin \left( 67.5\right) } \times \sin \left( 45\right) ==6.888301782572[/tex]
