(a) The value of the unknown length, a, is 18 cm
(b) The value of the unknown angle measurement, θ, is 39°
Law of sines
From the question, we are to determine the unknown length and angle measurement
(a)
A + B + C = 180° (Sum of angles in a triangle)
A = 180° - (B + C)
A = 180° -(68° + 59°)
A = 53°
Using the law of sines
[tex]\frac{a}{sin A}=\frac{c}{sin C}[/tex]
[tex]\frac{a}{sin 53^\circ}=\frac{19.5}{sin 59^\circ}[/tex]
[tex]a=\frac{19.5 \times sin 53^\circ}{sin 59^\circ}[/tex]
[tex]a= 18.168[/tex]
[tex]a \approx 18 cm[/tex]
(b)
[tex]\frac{sin A}{a}=\frac{sin B}{b}[/tex]
[tex]\frac{sin \theta}{15}=\frac{sin 57^\circ}{20}[/tex]
[tex]sin \theta=\frac{15 \times sin 57^\circ}{20}[/tex]
[tex]sin \theta=0.6290[/tex]
[tex]\theta=sin ^{-1} (0.6290)[/tex]
[tex]\theta=38.976 ^\circ[/tex]
[tex]\theta \approx 39^\circ[/tex]
Hence, the value of the unknown length, a, is 18 cm
The value of the unknown angle measurement, θ, is 39°
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