Out of 31 questions these are ones I struggled with. after the = sign is what I think the answer( except for #4, I don't know what to do at all), is so if I'm wrong can someone correct it with an explanation/formula with it please?

1.) Find the area of the parallelogram. ( base(s)=10cm, side length(s)=6cm, height=? and the angle of elevation=60'
a.)15√3 cm^2
b.)30√3 cm^2
c.)15√2 cm^2
=30√3 cm^2

2.) What is the length of the radius of a circle with the center at O(-3,4) and passes through the point P(2,-5)?
a.)9
b.)12.5
c.)10.3
=9

3.) What is the equation for a circle with a diameter having the following endpoints: N(0,1) and Q(18,1)?
a.)(x - 9)^2 + (y - 1)^2 = 81
b.)(x)^2 + (y)^2 = 72
c.)(x + 2)^2 + (y - 7)^2 = 56
=(x)^2 + (y)^2 = 72

4.) Using coordinate geometry to prove that the diagonals of a square are perpendicular to each other.
Given: Vertices are at A(0,0), B(a,0), C(a,a) and D(0,a) Slope of AC=1; Slope of BD=-1

Type your proof into the text box below.
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