For triangle DEF,
m∠D = 21°
m∠E = 87°
DF = 16
For triangle RST,
m∠S = 68°
m∠T = 57°
Simple polygons with three sides and three internal angles make up triangles. It is one of the fundamental geometric shapes in which the three vertices are connected to one another.
For ΔDEF, it is given that, m∠F = 72°, DE=15,EF=17.
By the law of cosines,
side DF=(a2+b2﹣2abcosγ)1/2
DF=16
Similarly,
m∠D = 21°
As the sum of angles of triangle is 180,
m∠E = 87°
For ΔRST, it is given that, m∠R = 55°, RS=17,RT=9.
By the law of cosines,
side ST=(a2+b2﹣2abcosγ)1/2
ST=16
Similarly,
m∠S = 68°
As the sum of angles of triangle is 180,
m∠T = 57°
Learn more about triangles here:
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