A triangle problem to calculate

Geometry Level 3

Calculate the length of DH to 2 decimal places if the sides are:
a=73.94
b=71.22
c=44.76

33.81 33.04 32.87 34.12

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

By law of cosines

44.7 6 2 = 71.2 2 2 + 73.9 4 2 2 ( 71.22 ) ( 73.94 ) cos C 44.76^2=71.22^2+73.94^2-2(71.22)(73.94) \cos C

cos C = 8989 11091 \cos C=\dfrac{8989}{11091} \implies C = cos 1 ( 8989 11091 ) 35.8 6 C= \cos^{-1}\left(\dfrac{8989}{11091}\right) \approx 35.86^\circ

Consider right A H C \triangle AHC :

cos C = C H 71.22 \cos C=\dfrac{CH}{71.22} , however, cos C = ( 8989 11091 ) \cos C=\left(\dfrac{8989}{11091}\right) , so

C H 71.22 = 8989 11091 \dfrac{CH}{71.22}=\dfrac{8989}{11091} \implies C H 57.72 CH \approx57.72

Consider right H D C \triangle HDC :

sin C = D H C H \sin C=\dfrac{DH}{CH}

sin 35.8 6 = D H 57.72 \sin 35.86^\circ=\dfrac{DH}{57.72}

D H DH \approx 33.81 \boxed{33.81}

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...