Answer:
is isosceles.
Step-by-step explanation:
Please have a look at the attached figure.
We are <u>given</u> the following things:


Let us try to find out
and
. After that we will compare them.
<u>Finding </u>
<u>:</u>
Side EG is a straight line so 
is sum of internal
and external 
<u>Finding </u>
<u>:</u>
<u>Property of external angle:</u> External angle in a triangle is equal to the sum of two opposite internal angles of a triangle.
i.e. external
= 

Comparing equations (1) and (2):
It can be clearly seen that:

The two angles of
are equal hence
is isosceles.
Answer:
C.
Step-by-step explanation:
A. 39 = 3 × 13; not prime
B. 33 = 3 × 11; not prime
C. 43 = 1 × 43; prime
D. 51 = 3 × 17; not prime
Answer: C.
The law of optics applicable in this scenario is the Snell's Law which states that the ratio of the index of refraction of two media is equal to the ratio of the sine of the angle of reflection and sine of the angle of refraction. In equation form:
n₁ / n₂ = sin b / sin a