We cannot know.
No siree
The questioner neglected to include the drawing that accompanied the question in his textbook,so we don't know where point 'D' is ? ? ?
15
7.2
Three triangles are: scalene, which has three sides of different lengths, isosceles, which has two sides with the same length, and equilateral, which has three sides that are all the same length. In the picture, the scalene triangle is triangle RST, the isosceles triangle is triangle XYZ, and the equilateral triangle is triangle ABC. If two sides or more sides of a triangle have a little line on them, then they are the same length. Click on the related link, "Three Triangles", to see them.
5
25
In order to find length BC the length of AC or length of the hypotenuse must be given
no
A triangle has 3 sides and so the length of bc will depend on its perimeter.
No siree
It can be but need not be.
The questioner neglected to include the drawing that accompanied the question in his textbook,so we don't know where point 'D' is ? ? ?
yes
Triangle ABC would be an isosceles. An isosceles triangle is defined as having two sides of equal length. This would also mean, then, that two angles in the triangle are also the same.
If you are really talking about a closed triangle ABC, then the length of side "a" (given as 19) does not matter in the calculation. Sum of the angles of a triangle is 180 degrees. Angle B and C add up to 15 + 65 = 80 degrees. Hence angle A is (180 - 80) = 100 degrees
12