+0  
 
0
934
2
avatar

the perimeter of a triangle is 60 cm one of its sides is 23 cm another is 24 cm calculate the size of the smallest angle in this triangle giving your answer to 1 decimal place

 May 29, 2015

Best Answer 

 #2
avatar+128460 
+5

The remaining side = 13cm

 

And the smallest angle will be opposite this side....so ....using the Law of Cosines  and the cosine inverse, we have

 

cos-1  ((13^2 - 24^2 -23^2) / ((-2)(24)(23) )  = Θ  = about 32.0°

 

 

 May 30, 2015
 #1
avatar+14913 
+5

Hello anonymous!

 

a = 23 cm; b = 24 cm ; P = 60 cm

c = P - b - a = (60 - 24 - 23) cm = 13 cm

 

c² = a² + b² - 2ab * cos γ

2ab * cosγ = a² + b² - c² 

cos γ = (a² + b² - c²) / 2ab

 

cos γ = (23² + 24² - 13²) cm² / 2 * 23 * 24 cm²

cos γ = 0,847826086958

γ = arc cos 0,847826086958

γ = 32,024°  

 

The smallest angle in this triangle is γ = 32,024°

 

With regards, asinus  :- )

 May 30, 2015
 #2
avatar+128460 
+5
Best Answer

The remaining side = 13cm

 

And the smallest angle will be opposite this side....so ....using the Law of Cosines  and the cosine inverse, we have

 

cos-1  ((13^2 - 24^2 -23^2) / ((-2)(24)(23) )  = Θ  = about 32.0°

 

 

CPhill May 30, 2015

0 Online Users