Even though ISG didn't need any help on this problem, it might be an interesting one to look at.
Area of ABC can be expressed as
(1/2)xy sin (70) = 30
xy = 60 / sin(70)
So....the area of PQR =
(1/2)xy sin (110) subbing for xy, we have
(1/2)[ 60 / sin (70)] * sin(110) ⇒ note that sin(70) = sin(110) .....so....
Area of PQR = (1/2) 60 = 30
Let the base of triangle ABC be " x ".
Now, let's draw a height from side x to angle C .
This makes a right triangle with the hypotenuse of y .
sin 70° = opposite / hypotenuse
sin 70° = height / y
y sin 70° = height
area of triangle ABC = (1/2)(base)(height)
area of triangle ABC = (1/2)(x)(y sin 70°) This equals 30 because the problem says so.
Now let's look at triangle PQR. Let the base be x .
This makes its height = y sin 110°
And the area of PQR = (1/2)(x)(y sin 110°)
Let's say
30 = (1/2)(x)(y sin 70°)
a = (1/2)(x)(y sin 110°) We want to know what a equals.
30 / a = [ (1/2)(x)(y sin 70°) ] / [ (1/2)(x)(y sin 110°) ]
30 / a = sin 70° / sin 110°
30 / a = 1
30 = a
Thanks so so sooo much! Just one question, how did you know what sin 70 divided by sin 110 is?
sin(110°) = sin(180° - 70°) → sin(180°)*cos(70°) - sin(70°)*cos(180°) → 0*cos(70°) - sin(70°)*(-1) → sin(70°)
So sin(70°)/sin(110°) = 1
.
Now that I think about it, 70 and 110 are both 20 degrees from 90, so their sines are equal.