You need three non-collinear points to name a plane.
Non-collinear means "not on the same straight line". So these three points can't all lie on the same straight line. If three points do lie on the same straight line, then it is impossible to generate a single unique plane.
(a) the given triangle is a isosceles triangle, therefore the two leg sides will be congruent, as well as the two base angles. It is given that one of the base angles ∠XYW is 70°, therefore, due to the law of a isosceles triangle, the measurement of ∠XWY is also 70°. Remember, a triangle's interior angles add up to 180°, so:
180 - (70 + 70) = 180 - 140 = 40
40° is your answer.
m∠X = 40°
(b) All sides are congruent, making it a equilateral triangle. If it is a equilateral triangle, then all the angles also have the same measurement. The total of the interior angle's measurement is 180°. Divide by the amount of angles, 3:
180/3 = 60
60° is your answer.
m∠V = 60°
~
(1)
given 
= 
( cross- multiply )
10j = 54 ( divide both sides by 10 )
j = 
= 
← in simplest form
(9)
let h be the hours worked daily , then
3h = 20 
= 
( divide both sides by 3 )
h = ÷ 3
= × 
= 
= 6 
She worked 6 hours each day
