In triangleABC,AB= 7 cm,BC= 5 cm andAَBC= 136ْ .

http://img27.imageshack.us/img27/2061/34515568.jpg

(i) Calculate the lenght ofAC.

(ii) Calculate the area of the triangleABC.

plz

tell me hw to solve these question

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- Mar 12th 2009, 04:18 AMelmysterioTriangle problem
**In triangle***ABC,AB*= 7 cm,*BC*= 5 cm and*AَBC*= 136ْ .

**http://img27.imageshack.us/img27/2061/34515568.jpg**

**(i) Calculate the lenght of***AC*.

**(ii) Calculate the area of the triangle***ABC.*

*plz*

*tell me hw to solve these question* - Mar 12th 2009, 08:00 AMTangera
Hello! I shall do part (a) first...

Have you learnt Cosine Rule?

Basically Cosine Rule states that (in the context of this question):

Therefore, by applying Cosine Rule, we can find AC:

[rounded off to 5 significant figures] = 11.2 cm [rounded off to 3 significant figures] - Mar 12th 2009, 08:07 AMTangera
Okay now for part (b)...

The formula for area of triangle is (in the context of the question):

Area of triangle ABC

In general, the formula is Area of triangle , where a and b are adjacent sides of a triangle and C is the angle opposite side c (i.e. the angle between sides a and b).

By applying this formula, we can answer the question:

Area of triangle ABC = = (rounded off to 3 significant figures)

Hope this helps! ^^