BD is 31 degrees because it is the same.
ADB is 90-31 because it is a right angle ( 59 degrees)
DEC is 180 - (31*2) because the 180 is of the trangle and the 31 is the same on the other side so times 2 then removed from 180
x = r sin θ cos Ф
x² = r² sin² θ cos² Ф
y = r sin θ sin Ф
y² = r² sin² θ sin² Ф
z = r cos θ
z² = r² cos² θ
x² + y² + z²
= r² sin² θ cos² Ф + r² sin² θ sin² Ф + r² cos² θ
= r² sin² θ (cos² Ф + sin² Ф) + r² cos² θ
= r² sin² θ + r² cos² θ
= r² (sin² θ + cos² θ)
= r² √
u = 10.4 and v = 12
Solution:
In the given 2 sides of a triangle are 60°, 60°.
Sum of all the angles of a triangle = 180°
60° + 60° + third angle = 180°
⇒ third angle = 180° – 60° – 60°
⇒ third angle = 60°
All angles are equal, therefore the given triangle is an equilateral triangle.
⇒ All sides are equal in length.
⇒ v = 12
The line drawn from the top angle divides the triangle into two equal parts
and the line is perpendicular.
12 ÷ 2 = 6
Using Pythagoras theorem,

⇒ 
⇒ 
⇒ 
⇒ 
⇒ u = 10.4
Hence, u = 10.4 and v = 12.
They are multiplicative inverses. For example, the reciprocal of 2/3 is 3/2. They are used when dividing fractions