If a+b+c=15 and a²+b²+c²=83 then the value of a³+b³+c³-3abc

The angle of elevation of the sun, when the length of the shadow  of a tree √3 times the height of the tree, is:

Direction: Study the double bar graph given below and answer the questions.

The class having maximum number of participants in exhibitions:

Each question below is followed by two statements A and B. You have to determine whether the data given in the statement is sufficient for answering the question. You should use the data and your knowledge of Mathematics to choose the best possible answer.
Give answer (A) if the statement A alone is sufficient to answer the question, but statement B alone is not sufficient.
Give answer (B) if the statement B alone is sufficient to answer the question, but statement A alone is not sufficient.
Give answer (C) if both statements A and B together are needed to answer the question.
Give answer (D) if either the statements A alone or statement B alone is sufficient to answer the question
Give answer (E) if you cannot get the answer from the statements A and B together, but need even more data.

Triangle ABC has angle BAC equal to 90°. What is the measure of the angle ABC?
A. The angle ACB is 35°
B. The angle CBA is 55°

A man standing on the bank of river observes that the angle subtended by a tree on the opposite bank is 60°. When he retrieves 36 m from the bank, he find that the angle is 30°. The breadth of the river is

If the area of a triangle is 1176 cm² and the ratio of base corresponding altitude is 3 : 4, then the altitude of the triangle is :

If a : b = 20:5 then find out the value of (13a-9b): (11a-7b)?