Thursday

July 24, 2014

July 24, 2014

Posted by **please help me out!!!!** on Monday, February 18, 2013 at 12:36am.

- geometry! -
**Reiny**, Monday, February 18, 2013 at 12:57amI placed D outside the triangle top-right of A, joined CD and AD

In triangle ABC , it is easy to see that angle ACB = 42°

and if angle DCA= 48° , then angle BCD = 90°

(this helps to make a reasonable sketch)

Suppose we let AC = 5 (anything will do)

then by the sine law:

BC/sin96 = 5/sin42

BC = 7.43145 (I stored that in my calculator)

now switch to triangle ACD

sinD/AC = sin48/AD , but AD = BC = 7.431...

and AC = 5

SinD/5 = sin48/7.431..

sinD = .5

D = 30° , ahhh!!!

then angle DAC = 180+48+30 = 102°

**Related Questions**

Math (Geometry) - In triangle ABC, ∠A=20∘ and ∠B=80∘. ...

geometry!!! please help me!!!! - ABC is a triangle with ∠ACB=45∘. D ...

geometry! - ABC is an acute angle triangle with points D and E on BC and AC, ...

geoMETRY! - ABC is an acute angle triangle with points D and E on BC and AC, ...

heeeeeeeelp math - In triangle ABC, ∠A=20∘ and ∠B=80∘. ...

simple GEOMETRY!! - In triangle ABC, ∠ABC=30∘,∠ACB=60∘. ...

Math (Geometry) - ABCD is a parallelogram with side lengths AB=15,BC=10 and &#...

geometry(triangle) - Triangle ABC is a right triangle with ∠ABC=90∘...

Maths - ABCD is a parallelogram with side lengths AB=15,BC=10 and ∠ADC=75...

Math - In triangle ABC, points D,E,F are on sides BC,CA,AB respectively such ...