The triangle PQR isn't a square triangle.

PQ = 9.9cm

QR = 22.3cm

RP = 18.1cm

(Going around the triangle anti clockwise)

P

Q R

Calculate the area of the triangle.

Please help me and state how you did it :)

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- May 27th 2008, 02:07 PMiwzSimple Triangle Question
The triangle PQR isn't a square triangle.

PQ = 9.9cm

QR = 22.3cm

RP = 18.1cm

(Going around the triangle anti clockwise)

P

Q R

Calculate the area of the triangle.

Please help me and state how you did it :) - May 27th 2008, 02:50 PMsean.1986
Cosine rule....

a^2 = b^2 + c^2 - 2bcCosA

2bcCosA = b^2 + c^2 - a^2

CosA = (b^2 + c^2 - a^2) / 2bc

CosA = (9.9^2 + 22.3^2 - 18.1^2) / 441.51

A = arccos((9.9^2 + 22.3^2 - 18.1^2) / 441.51) = 0.919389657 radians

Area = 0.5bcSinA = 87.8 cm^2 - May 27th 2008, 03:08 PMTheEmptySet
- May 28th 2008, 12:15 PMiwz