Posted by lin on Friday, July 5, 2013 at 8:33am.
In triangle ABC, ∠A=20∘ and ∠B=80∘. Let
D be a point on line segment AB such that
AD=BC. What is the measure (in degrees) of ∠ADC?
- heeeeeeeelp math - MathMate, Friday, July 5, 2013 at 10:51am
=> isosceles triangle with base BC=x.
Let E=mid-point of BC, then
ΔAEC is a right triangle right-angled at E
By definition of cosine,
AC=x/(2cos(80°)) (from above)
we find DC by cosine rule
∠ ADC can be found by the sine rule:
Please check my arithmetic.
Answer This Question
More Related Questions
- Math (Geometry) - In triangle ABC, ∠A=20∘ and ∠B=80∘. ...
- Math (Geometry) - ABCD is a parallelogram with side lengths AB=15,BC=10 and ...
- Maths - ABCD is a parallelogram with side lengths AB=15,BC=10 and ∠ADC=75...
- geometry!!! please help me!!!! - ABC is a triangle with ∠ACB=45∘. D ...
- geometry - ABCD is a rectangle. On line segment AB, E is a point such that ...
- 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, ...
- geometry! - ABC is an isosceles triangle with AB=AC, ∠BAC=96∘. D is ...
- simple GEOMETRY!! - In triangle ABC, ∠ABC=30∘,∠ACB=60∘. ...
- geometry(triangle) - Triangle ABC is a right triangle with ∠ABC=90∘...